U.S. patent application number 16/925437 was filed with the patent office on 2021-01-21 for battery monitoring apparatus.
This patent application is currently assigned to DENSO CORPORATION. The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Masakatsu HORIGUCHI, Masaaki KITAGAWA.
Application Number | 20210018567 16/925437 |
Document ID | / |
Family ID | 1000004988161 |
Filed Date | 2021-01-21 |
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United States Patent
Application |
20210018567 |
Kind Code |
A1 |
HORIGUCHI; Masakatsu ; et
al. |
January 21, 2021 |
BATTERY MONITORING APPARATUS
Abstract
A battery monitoring apparatus includes an electric power supply
terminal connected with a first electrical path, a voltage input
terminal connected with a second electrical path, a signal control
unit connected with a third electrical path, a response signal
input terminal connected with a fourth electrical path, and a
calculating unit. The signal control unit is configured to cause a
predetermined AC signal to be outputted from a storage battery with
the storage battery itself being an electric power source for the
output of the predetermined AC signal. The calculating unit is
configured to calculate, based on a response signal of the storage
battery to the predetermined AC signal, a complex impedance of the
storage battery. Moreover, at least one of the first to the fourth
electrical paths is merged with at least one of the other
electrical paths into an electrical path that is connected to the
storage battery.
Inventors: |
HORIGUCHI; Masakatsu;
(Kariya-city, JP) ; KITAGAWA; Masaaki;
(Kariya-city, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city |
|
JP |
|
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
1000004988161 |
Appl. No.: |
16/925437 |
Filed: |
July 10, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R 31/389 20190101;
G01R 31/382 20190101; G01R 31/392 20190101; G01R 31/3648 20130101;
G01R 27/02 20130101; H01M 2220/20 20130101; H02J 7/0047 20130101;
G01R 31/396 20190101; H02J 7/0013 20130101; H01M 10/482
20130101 |
International
Class: |
G01R 31/36 20060101
G01R031/36; G01R 31/382 20060101 G01R031/382; G01R 31/389 20060101
G01R031/389; G01R 31/392 20060101 G01R031/392; G01R 31/396 20060101
G01R031/396; H01M 10/48 20060101 H01M010/48; G01R 27/02 20060101
G01R027/02; H02J 7/00 20060101 H02J007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 19, 2019 |
JP |
2019-133548 |
Claims
1. A battery monitoring apparatus for monitoring a state of a
storage battery, the battery monitoring apparatus comprising: an
electric power supply terminal which is connected with a first
electrical path and via which drive electric power is supplied from
the storage battery to the battery monitoring apparatus through the
first electrical path; a voltage input terminal which is connected
with a second electrical path and via which a terminal voltage of
the storage battery is inputted to the battery monitoring apparatus
through the second electrical path so as to be measured by the
battery monitoring apparatus; a signal control unit connected with
a third electrical path and configured to cause a predetermined AC
signal to be outputted from the storage battery through the third
electrical path; a response signal input terminal which is
connected with a fourth electrical path and via which a response
signal of the storage battery to the AC signal is inputted to the
battery monitoring apparatus through the fourth electrical path;
and a calculating unit configured to calculate, based on the
response signal, a complex impedance of the storage battery,
wherein the signal control unit is configured to cause the
predetermined AC signal to be outputted from the storage battery
with the storage battery itself being an electric power source for
the output of the predetermined AC signal, and at least one of the
first electrical path, the second electrical path, the third
electrical path and the fourth electrical path is merged with at
least one of the other electrical paths into an electrical path
that is connected to the storage battery.
2. The battery monitoring apparatus as set forth in claim 1,
wherein the first electrical path is merged with the third
electrical path into a fifth electrical path that is connected to
the storage battery.
3. The battery monitoring apparatus as set forth in claim 1,
wherein the second electrical path is provided separately from the
first electrical path and the third electrical path.
4. The battery monitoring apparatus as set forth in claim 1,
wherein the fourth electrical path is provided separately from the
first electrical path and the third electrical path.
5. The battery monitoring apparatus as set forth in claim 1,
wherein the second electrical path is merged with the fourth
electrical path into a sixth electrical path that is connected to
the storage battery.
6. The battery monitoring apparatus as set forth in claim 1,
wherein storage-battery-side end portions of the electrical paths
are respectively joined to different portions of an electric power
supply terminal of the storage battery, and among the different
portions of the electric power supply terminal of the storage
battery, the portion to which the storage-battery-side end portion
of the electrical path connected with the response signal input
terminal is joined is located closest to an electrode of the
storage battery, the electrode of the storage battery being
connected with the electric power supply terminal of the storage
battery.
7. The battery monitoring apparatus as set forth in claim 1,
wherein the storage battery is included in a battery pack, the
battery pack includes a plurality of storage batteries each having
a pair of electric power supply terminals, each corresponding pair
of the electric power supply terminals of the plurality of storage
batteries are connected with each other via a busbar, and at least
a storage-battery-side end portion of the electrical path connected
with the response signal input terminal is directly joined to a
corresponding one of the electric power supply terminals of the
storage battery whose state is monitored by the battery monitoring
apparatus, without any busbar interposed between the
storage-battery-side end portion of the electrical path and the
corresponding electric power supply terminal of the storage
battery.
8. The battery monitoring apparatus as set forth in claim 1,
wherein the storage battery is included in a battery pack, the
battery pack includes a plurality of storage batteries each having
a pair of positive and negative electrodes and a pair of
positive-electrode-side and negative-electrode-side electric power
supply terminals connected respectively with the positive and
negative electrodes, each corresponding pair of the
positive-electrode-side and negative-electrode-side electric power
supply terminals of the plurality of storage batteries are
connected with each other via a busbar so that all the plurality of
storage batteries are electrically connected in series with each
other, the battery monitoring apparatus comprises a plurality of
sets of the voltage input terminal, the signal control unit, the
response signal input terminal and the second to the fourth
electrical paths, each set being provided to monitor a state of a
corresponding one of the plurality of storage batteries, and the
electric power supply terminal and the first electrical path both
of which are shared by all the plurality of storage batteries, the
electric power supply terminal of the battery monitoring apparatus
comprises a positive-electrode-side electric power supply terminal
and a negative-electrode-side electric power supply terminal, the
first electrical path comprises a positive-electrode-side first
electrical path connected with the positive-electrode-side electric
power supply terminal of the battery monitoring apparatus and a
negative-electrode-side first electrical path connected with the
negative-electrode-side electric power supply terminal of the
battery monitoring apparatus, the positive-electrode-side first
electrical path is merged with the third electrical path that is
connected with the positive-electrode-side electric power supply
terminal of one of the plurality of storage batteries which has a
highest electric potential in the battery pack, and the
negative-electrode-side first electrical path is merged with the
third electrical path that is connected with the
negative-electrode-side electric power supply terminal of one of
the plurality of storage batteries which has a lowest electric
potential in the battery pack.
9. The battery monitoring apparatus as set forth in claim 1,
wherein the storage battery is included in a battery pack, the
battery pack includes a plurality of storage batteries each having
a pair of positive and negative electrodes and a pair of
positive-electrode-side and negative-electrode-side electric power
supply terminals connected respectively with the positive and
negative electrodes, the signal control unit has a
positive-electrode-side terminal and a negative-electrode-side
terminal, the third electrical path comprises a
positive-electrode-side third electrical path connected with the
positive-electrode-side terminal of the signal control unit and a
negative-electrode-side third electrical path connected with the
negative-electrode-side terminal of the signal control unit, the
battery monitoring apparatus comprises a plurality of sets of the
signal control unit and the third electrical path, each set being
provided to monitor a state of a corresponding one of the plurality
of storage batteries, the plurality of storage batteries include a
first storage battery and a second storage battery that are
arranged adjacent to each other, the negative-electrode-side
electric power supply terminal of the first storage battery is
connected with the positive-electrode-side electric power supply
terminal of the second storage battery via a busbar, and the
negative-electrode-side third electrical path connected with the
negative-electrode-side terminal of the signal control unit
corresponding to the first storage battery is merged with the
positive-electrode-side third electrical path connected with the
positive-electrode-side terminal of the signal control unit
corresponding to the second storage battery into an electrical path
that is connected to the busbar.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims priority from
Japanese Patent Application No. 2019-133548 filed on Jul. 19, 2019,
the contents of which are hereby incorporated by reference in their
entirety into this application.
BACKGROUND
1 Technical Field
[0002] The present disclosure relates to battery monitoring
apparatuses.
2 Description of Related Art
[0003] There is known a technique of measuring the complex
impedance of a storage battery and thereby monitoring a state of
the storage battery. Specifically, according to this technique, a
rectangular-wave signal is applied to the storage battery. Then,
the complex impedance characteristics of the storage battery are
calculated based on a response signal of the storage battery to the
rectangular-wave signal. Thereafter, the SOH (i.e., state of
health) of the storage battery is determined based on the
calculated complex impedance characteristics.
SUMMARY
[0004] According to the present disclosure, there is provided a
battery monitoring apparatus for monitoring a state of a storage
battery. The battery monitoring apparatus includes:
[0005] an electric power supply terminal which is connected with a
first electrical path and via which drive electric power is
supplied from the storage battery to the battery monitoring
apparatus through the first electrical path;
[0006] a voltage input terminal which is connected with a second
electrical path and via which a terminal voltage of the storage
battery is inputted to the battery monitoring apparatus through the
second electrical path so as to be measured by the battery
monitoring apparatus;
[0007] a signal control unit connected with a third electrical path
and configured to cause a predetermined AC signal to be outputted
from the storage battery through the third electrical path;
[0008] a response signal input terminal which is connected with a
fourth electrical path and via which a response signal of the
storage battery to the AC signal is inputted to the battery
monitoring apparatus through the fourth electrical path; and
[0009] a calculating unit configured to calculate, based on the
response signal, a complex impedance of the storage battery,
[0010] wherein
[0011] the signal control unit is configured to cause the
predetermined AC signal to be outputted from the storage battery
with the storage battery itself being an electric power source for
the output of the predetermined AC signal, and
[0012] at least one of the first electrical path, the second
electrical path, the third electrical path and the fourth
electrical path is merged with at least one of the other electrical
paths into an electrical path that is connected to the storage
battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic configuration diagram of an electric
power supply system.
[0014] FIG. 2 is a configuration diagram of a battery monitoring
apparatus according to a first embodiment.
[0015] FIG. 3 is a flow chart illustrating a complex impedance
calculating process according to the first embodiment.
[0016] FIG. 4 is a schematic diagram illustrating the electrical
connection between a battery cell and the battery monitoring
apparatus according to the first embodiment.
[0017] FIG. 5A is a schematic diagram illustrating undesirable
locations at which response signal input terminals of the battery
monitoring apparatus could be connected respectively to electric
power supply terminals of the battery cell.
[0018] FIG. 5B is a schematic diagram illustrating desirable
locations at which the response signal input terminals of the
battery monitoring apparatus are connected respectively to the
electric power supply terminals of the battery cell.
[0019] FIG. 6 is a configuration diagram of a battery monitoring
apparatus according to a second embodiment.
[0020] FIG. 7 is a flow chart illustrating a complex impedance
calculating process according to the second embodiment.
[0021] FIG. 8 is a configuration diagram of a battery monitoring
apparatus according to a third embodiment.
[0022] FIG. 9 is a flow chart illustrating a complex impedance
calculating process according to the third embodiment.
[0023] FIG. 10 is a configuration diagram of a battery monitoring
apparatus according to a fourth embodiment.
[0024] FIG. 11 is a schematic diagram illustrating the electrical
connection between battery cells and the battery monitoring
apparatus according to the fourth embodiment.
[0025] FIG. 12 is a configuration diagram of a battery monitoring
apparatus according to a fifth embodiment.
[0026] FIG. 13 is a schematic diagram illustrating the electrical
connection between battery cells and the battery monitoring
apparatus according to the fifth embodiment.
[0027] FIG. 14 is a configuration diagram of a battery monitoring
apparatus according to a sixth embodiment.
[0028] FIG. 15 is a configuration diagram of a battery monitoring
apparatus according to a modification.
[0029] FIG. 16 is a flow chart illustrating a complex impedance
calculating process according to another modification.
[0030] FIG. 17 is a schematic diagram illustrating the electrical
connection between a battery cell and a battery monitoring
apparatus according to yet another modification.
[0031] FIG. 18 is a schematic diagram illustrating a circuit board
of a battery monitoring apparatus according to still another
modification.
DESCRIPTION OF EMBODIMENTS
[0032] The inventors of the present application have found that the
following problems may occur when the above-described technique
known in the art (see, for example, Japanese Patent No.
JP6226261B2) is used in a battery monitoring apparatus to measure
the complex impedance of a vehicular storage battery. That is, it
is necessary to employ a device, such as a power controller, for
applying the rectangular-wave signal to the storage battery. The
employment of such a device will cause the size and manufacturing
cost of the battery monitoring apparatus to be increased. Moreover,
it is necessary to provide in the battery monitoring apparatus
various terminals, such as terminals for inputting/outputting
electric power, terminals for outputting signals to the storage
battery, terminals for measuring the voltage of the storage battery
and terminals for measuring the response signal of the storage
battery. Consequently, the number of terminals of the battery
monitoring apparatus will become large, increasing the time and
cost for connecting the terminals of the battery monitoring
apparatus to electric power supply terminals of the storage battery
during the assembly of the battery monitoring apparatus to the
storage battery. This problem is remarkable particularly when the
above technique is used to monitor a state of a vehicular battery
pack that is composed of a plurality of storage batteries.
[0033] In contrast, in the above-described battery monitoring
apparatus according to the present disclosure, the signal control
unit causes the predetermined AC signal to be outputted from the
storage battery with the storage battery itself being the electric
power source for the output of the predetermined AC signal.
Consequently, it becomes unnecessary to employ an external electric
power source for applying a disturbance to the storage battery
(i.e., causing the predetermined AC signal to be outputted from the
storage battery) for the purpose of measuring the complex impedance
of the storage battery. As a result, it becomes possible to reduce
the parts count and the size of the battery monitoring apparatus,
thereby lowering the manufacturing cost.
[0034] Moreover, to an in-vehicle storage battery, there are
generally connected peripheral devices such as a protective element
and a filter circuit. Therefore, when an AC signal is inputted as a
disturbance to the storage battery, part of the AC signal may be
leaked to the peripheral devices. Consequently, if the complex
impedance of the storage battery is calculated based on a response
signal of the storage battery to the inputted AC signal, it might
be impossible to ensure the accuracy of calculation of the complex
impedance due to an error in the response signal caused by the
leakage of the AC signal.
[0035] In contrast, with the above configuration of the battery
monitoring apparatus according to the present disclosure, the
signal control unit causes the predetermined AC signal to be
outputted from the storage battery with the storage battery itself
being the electric power source for the output of the predetermined
AC signal. Consequently, it becomes possible to realize a closed
circuit with the signal control unit and the storage battery. As a
result, it becomes possible to eliminate current leakage from the
storage battery to the peripheral devices, thereby suppressing
occurrence of an error in the response signal.
[0036] Furthermore, with the above configuration, at least one of
the first electrical path, the second electrical path, the third
electrical path and the fourth electrical path is merged with at
least one of the other electrical paths. Consequently, it becomes
possible to reduce the number of the electrical paths of the
battery monitoring apparatus joined to electric power supply
terminals of the storage battery. As a result, it becomes possible
to reduce the time and cost for joining the electrical paths to the
electric power supply terminals during the assembly of the battery
monitoring apparatus to the storage battery.
[0037] Exemplary embodiments will be described hereinafter with
reference to the drawings. It should be noted that for the sake of
clarity and understanding, identical components having identical
functions throughout the whole description have been marked, where
possible, with the same reference numerals in each of the figures
and that for the sake of avoiding redundancy, descriptions of
identical components will not be repeated.
First Embodiment
[0038] FIG. 1 shows the overall configuration of an electric power
supply system 10 which is provided in a vehicle (e.g., a hybrid
vehicle or an electric vehicle) and in which battery monitoring
apparatuses 50 according to the first embodiment are employed.
[0039] As shown in FIG. 1, the electric power supply system 10
includes a motor 20 that is a rotating electric machine, an
inverter 30 that functions as an electric power converter to supply
three-phase alternating current to the motor 20, a rechargeable
battery pack 40, battery monitoring apparatuses 50 for monitoring a
state of the battery pack 40, and an ECU 60 that controls the motor
20 and the inverter 30.
[0040] The motor 20 is a main machine of the vehicle. The motor 20
is mechanically connected with driving wheels (not shown) of the
vehicle so that mechanical power (or torque) can be transmitted
between the motor 20 and the driving wheels. In the present
embodiment, the motor 20 is implemented by a three-phase permanent
magnet synchronous motor.
[0041] The inverter 30 is configured with a full bridge circuit
having a plurality of pairs of upper and lower arms. The number of
pairs of the upper and lower arms is equal to the number of phase
windings of the motor 20. Each of the upper and lower arms has a
switch (or semiconductor switching element) provided therein. In
operation, electric current supplied to the phase windings of the
motor 20 is controlled by turning on/off the switches of the upper
and lower arms.
[0042] Specifically, an inverter controller (not shown) is provided
in the inverter 30. The inverter controller controls, based on
various types of information detected in the motor 20 and a power
running drive request (or torque generation request) or an electric
power generation request, the on/off of the switches in the
inverter 30, thereby controlling energization of the phase windings
of the motor 20. More specifically, the inverter controller
controls the supply of electric power from the battery pack 40 to
the motor 20 via the inverter 30, thereby driving the motor 20 to
operate in a power running mode (or torque generation mode).
Otherwise, when the motor 20 operates in an electric power
generation mode (i.e., the motor 20 is driven by mechanical power
transmitted from, for example, the driving wheels of the vehicle to
generate three-phase AC power), the inverter controller controls
the inverter 30 to function as a rectifier to rectify the
three-phase AC power generated by the motor 20 into a DC power; the
DC power is then supplied to the battery pack 40 to charge it.
[0043] That is, in the present embodiment, the motor 20 is
configured as a motor-generator that operates selectively in either
the power running mode or the electric power generation mode.
Moreover, the inverter 30 is configured as an electric power
converter that functions selectively as either an inverter or a
rectifier.
[0044] The battery pack 40 is electrically connected with the motor
20 via the inverter 30. The battery pack 40 has a terminal voltage
(i.e., voltage between two terminals) higher than or equal to, for
example 100V The battery pack 40 is configured with a plurality of
battery modules 41 that are connected in series with each other.
Moreover, each of the battery modules 41 is configured with a
plurality of battery cells 42 that are connected in series with
each other. The battery cells 42 may be implemented by, for
example, lithium-ion batteries or nickel-metal hydride batteries.
That is, each of the battery cells 42 is a storage battery which
includes an electrolyte and a pair of electrodes.
[0045] To a positive-electrode-side electric power supply path L1
that is connected with a positive-electrode-side electric power
supply terminal of the battery pack 40, there are connected
positive-electrode-side terminals of electrical loads such as the
inverter 30. On the other hand, to a negative-electrode-side
electric power supply path L2 that is connected with a
negative-electrode-side electric power supply terminal of the
battery pack 40, there are connected negative-electrode-side
terminals of the electrical loads. Moreover, in each of the
positive-electrode-side and negative-electrode-side electric power
supply paths L1 and L2, there is provided an SMR (i.e., system main
relay) switch to selectively allow and interrupt flow of electric
current through the electric power supply path.
[0046] The battery monitoring apparatuses 50 are provided to
monitor the SOC (i.e., state of charge) and/or SOH (i.e., state of
health) of each of the battery cells 42. More particularly, in the
present embodiment, for each of the battery cells 42, there is
provided a corresponding one of the battery monitoring apparatuses
50 to monitor the SOC and/or SOH of the battery cell 42. The
battery monitoring apparatuses 50 are connected with the ECU 60 so
as to output the monitored states of the battery cells 42 to the
ECU 60. The configuration of the battery monitoring apparatuses 50
will be described in detail later.
[0047] The ECU 60 selectively makes, based on various types of
information, either the power running drive request or the electric
power generation request to the inverter controller. The various
types of information include, for example, accelerator operation
information, brake operation information, the vehicle speed and the
state of the battery pack 40.
[0048] Next, the configuration of each of the battery monitoring
apparatuses 50 according to the present embodiment will be
described with reference to FIG. 2. In addition, as mentioned
previously, in the present embodiment, for each of the battery
cells 42, there is provided a corresponding one of the battery
monitoring apparatuses 50.
[0049] As shown in FIG. 2, each of the battery monitoring
apparatuses 50 includes an ASIC (Application-Specific Integrated
Circuit) 50a, a filter unit 55 and a current modulation circuit
56.
[0050] The ASIC 50a includes a stabilized-electric power supply
unit 51, an input/output unit 52, a microcomputer 53 that functions
as a calculating unit, and a communication unit 54.
[0051] The stabilized-electric power supply unit 51 is connected
with electric power supply lines of the battery cell 42. The
stabilized-electric power supply unit 51 is configured to supply
electric power from the battery cell 42 to the input/output unit
52, the microcomputer 53 and the communication unit 54.
Consequently, the input/output unit 52, the microcomputer 53 and
the communication unit 54 operate on the electric power supplied by
the stabilized-electric power supply unit 51. The
stabilized-electric power supply unit 51 has a
positive-electrode-side terminal 51a and a negative-electrode-side
terminal 51b that function as electric power supply terminals via
which drive electric power is supplied from the battery cell 42 to
the battery monitoring apparatus 50.
[0052] The input/output unit 52 is connected with the battery cell
42 that is the monitoring target. Specifically, the input/output
unit 52 has DC voltage input terminals 57 via which the DC voltage
(or terminal voltage) of the battery cell 42 is inputted to (or
measured by) the battery monitoring apparatus 50. Between the
battery cell 42 and the DC voltage input terminals 57, there is
provided the filter unit 55. More specifically, the DC voltage
input terminals 57 consist of a positive-electrode-side input
terminal 57a and a negative-electrode-side input terminal 57b. On
the other hand, the filter unit 55 has RC (Resistor-Capacitor)
filters 55a as filter circuits and a Zener diode 55b as a
protective element. The RC filters 55a and the Zener diode 55b are
provided between the positive-electrode-side input terminal 57a and
the negative-electrode-side input terminal 57b of the input/output
unit 52. That is, the RC filters 55a and the Zener diode 55b are
connected in parallel with the battery cell 42. In addition, in the
present embodiment, the positive-electrode-side input terminal 57a
and the negative-electrode-side input terminal 57b function as
voltage input terminals via which the terminal voltage of the
battery cell 42 is inputted to and measured by the battery
monitoring apparatus 50.
[0053] Moreover, the input/output unit 52 also has response signal
input terminals 58 via which a response signal (or voltage
variation) indicative of the internal complex impedance information
of the battery cell 42 is inputted to the battery monitoring
apparatus 50. Specifically, the response signal input terminals 58
consist of a positive-electrode-side input terminal 58a and a
negative-electrode-side input terminal 58b that function as
response signal input terminals via which the response signal is
inputted to the battery monitoring apparatus 50.
[0054] Furthermore, the input/output unit 52 is connected with the
current modulation circuit 56 that functions as a signal control
unit. The input/output unit 52 has a command signal output terminal
59a via which a command signal is outputted to the current
modulation circuit 56; the command signal is indicative of a
command commanding the current modulation circuit 56 to cause a
predetermined sine-wave signal (or AC signal) to be outputted from
the battery cell 42. Moreover, the input/output unit 52 also has a
feedback signal input terminal 59b via which current signal, which
is actually outputted from (or actually flows out of) the battery
cell 42, is inputted as a feedback signal to the input/output unit
52 through the current modulation circuit 56.
[0055] The input/output unit 52 is also connected with the
microcomputer 53 so as to output to the microcomputer 53 the DC
voltage inputted via the DC voltage input terminals 57, the
response signal inputted via the response signal input terminals 58
and the feedback signal inputted via the feedback signal input
terminal 59b. In addition, the input/output unit 52 includes an AD
(Analog-to-Digital) converter (not shown) therein; the AD converter
is configured to convert inputted analog signals into digital
signals and output the resultant digital signals to the
microcomputer 53.
[0056] Moreover, the input/output unit 52 is configured to: input
the command signal from the microcomputer 53; and output the
command signal to the current modulation circuit 56 via the command
signal output terminal 59a. In addition, the input/output unit 52
also includes a DA (Digital-to-Analog) converter (not shown)
therein; the DA converter is configured to convert digital signals
inputted from the microcomputer 53 into analog signals and output
the resultant analog signals to the current modulation circuit
56.
[0057] In the present embodiment, a DC bias is applied to the
sine-wave signal, which is commanded by the command signal to the
current modulation circuit 56, so as to prevent the sine-wave
signal from becoming a negative current (or reverse current with
respect to the battery cell 42).
[0058] The current modulation circuit 56 is configured to cause a
predetermined AC signal (i.e., sine-wave signal) to be outputted
from the battery cell 42 that is the monitoring target, with the
battery cell 42 itself being the electric power source for the
output of the predetermined AC signal. Specifically, the current
modulation circuit 56 includes a semiconductor switch element
(e.g., a MOSFET) 56a and a resistor 56b connected in series with
the semiconductor switch element 56a. The semiconductor switch
element 56a has its drain terminal connected to a
positive-electrode-side electric power supply terminal 71a of the
battery cell 42 and its source terminal serially connected to one
end of the resistor 56b. Moreover, the other end of the resistor
56b is connected to a negative-electrode-side electric power supply
terminal 71b of the battery cell 42. The semiconductor switch
element 56a is configured to be capable of regulating the amount of
electric current flowing between its drain and its source.
[0059] In addition, the positive-electrode-side and
negative-electrode-side electric power supply terminals 71a and 71b
of the battery cell 42 are connected respectively with positive and
negative electrodes of the battery cell 42 (see FIGS. 5A-5B). It is
desirable for the response signal input terminals 58 to be
connected respectively to, of all connectable portions of the
electric power supply terminals 71a and 71b of the battery cell 42,
those connectable portions which are located closest to the
electrodes of the battery cell 42 (see FIG. 5B). Similarly, it is
desirable for the DC voltage input terminals 57 to be connected
respectively to those connectable portions of the electric power
supply terminals 71a and 71b which are located closest to the
electrodes or those connectable portions of the electric power
supply terminals 71a and 71b which are located second closest to
the electrodes with the response signal input terminals 58 being
connected to the closest connectable portions to the electrodes. In
these cases, it is possible to minimize the influence of a voltage
drop, which is caused by main current or equalization current, on
the response signal inputted to the battery monitoring apparatus 50
via the response signal input terminals 58 and the DC voltage
inputted to the battery monitoring apparatus 50 via the DC voltage
input terminals 57.
[0060] Moreover, in the current modulation circuit 56, there is
provided a current detection amplifier 56c which is connected to
both ends of the resistor 56b to function as a current detection
unit. Specifically, the current detection amplifier 56c is
configured to detect a signal (i.e., current signal) flowing
through the resistor 56b and output the detected signal as the
feedback signal to the feedback signal input terminal 59b of the
input/output unit 52.
[0061] Furthermore, in the current modulation circuit 56, there is
also provided a feedback circuit 56d. The feedback circuit 56d is
configured to: (1) input the command signal from the command signal
output terminal 59a of the input/output unit 52 and the feedback
signal from the current detection amplifier 56c; (2) compare the
command signal and the feedback signal; and (3) output a signal
indicative of the result of the comparison to a gate terminal of
the semiconductor switch element 56a.
[0062] Based on the signal outputted from the feedback circuit 56d,
the semiconductor switch element 56a regulates the voltage applied
between its gate and its source and thereby regulates the amount of
electric current flowing between its drain and its source, so as to
cause the sine-wave signal (or predetermined AC signal) commanded
by the command signal to be outputted from the battery cell 42. In
addition, when there is a deviation between the waveform of the
sine-wave signal commanded by the command signal and the waveform
of the sine-wave signal actually flowing through the resistor 56b,
the semiconductor switch element 56a regulates the amount of
electric current based on the signal outputted from the feedback
circuit 56d, thereby correcting the deviation. Consequently, the
sine-wave signal flowing through the resistor 56b can be
stabilized.
[0063] Next, a process of calculating the complex impedance of each
of the battery cells 42 according to the present embodiment will be
described with reference to FIG. 3. This process is repeatedly
performed by the corresponding battery monitoring apparatus 50 in a
predetermined cycle.
[0064] In the complex impedance calculating process, first, in step
S101, the microcomputer 53 of the corresponding battery monitoring
apparatus 50 sets a measurement frequency of the complex impedance
within a predetermined frequency range.
[0065] In step S102, the microcomputer 53 sets the frequency of the
sine-wave signal (or predetermined AC signal) based on the
measurement frequency set in step S101. Then, the microcomputer 53
outputs the command signal to the input/output unit 52. As
described previously, the command signal is indicative of a command
commanding the current modulation circuit 56 to cause the sine-wave
signal to be outputted from the battery cell 42.
[0066] Upon the command signal being inputted thereto, the
input/output unit 52 outputs the command signal, through the
digital-to-analog conversion by the DA converter, to the current
modulation circuit 56. Then, according to the command signal, the
current modulation circuit 56 causes the sine-wave signal to be
outputted from the battery cell 42 that is the monitoring target,
with the battery cell 42 itself being the electric power source for
the output of the sine-wave signal.
[0067] More specifically, in the current modulation circuit 56, the
semiconductor switch element 56a regulates the amount of electric
current based on the signal inputted thereto via the feedback
circuit 56d, so as to cause the sine-wave signal commanded by the
command signal to be outputted from the battery cell 42.
Consequently, the sine-wave signal is outputted from the battery
cell 42.
[0068] Upon the sine-wave signal being outputted from the battery
cell 42, in other words, upon application of a disturbance to the
battery cell 42, variation occurs in the voltage between the
terminals of the battery cell 42; the voltage variation is
indicative of the internal complex impedance information of the
battery cell 42. Then, the input/output unit 52 outputs the voltage
variation, which is inputted to the input/output unit 52 via the
response signal input terminals 58, as the response signal to the
microcomputer 53. More specifically, the input/output unit 52
outputs the response signal through the analog-to-digital
conversion by the AD converter.
[0069] In step S103, the microcomputer 53 receives the response
signal outputted from the input/output unit 52.
[0070] In step S104, the microcomputer 53 acquires the current
signal flowing through the resistor 56b of the current modulation
circuit 56 (i.e., the sine-wave signal outputted from the battery
cell 42). Specifically, the microcomputer 53 receives, via the
input/output unit 52, the feedback signal (or detected signal)
outputted from the current detection amplifier 56c as the current
signal.
[0071] In addition, instead of the feedback signal, a signal which
is proportional to the command signal outputted to the current
modulation circuit 56 may be used as the current signal.
[0072] In step S105, the microcomputer 53 calculates the complex
impedance of the battery cell 42 based on both the response signal
and the current signal. Specifically, the microcomputer 53
calculates at least one of the real part, the imaginary part, the
absolute value and the phase of the complex impedance on the basis
of the amplitude of the response signal and the phase difference of
the response signal from the current signal.
[0073] In step S106, the microcomputer 53 outputs the calculation
results to the ECU 60 via the communication unit 54. Then, the
complex impedance calculating process terminates.
[0074] The above calculating process is repeated until the complex
impedance of the battery cell 42 has been calculated with respect
to a plurality of measurement frequencies within the predetermined
frequency range. Based on the calculation results, the ECU 60
creates, for example, a complex impedance plane plot (or Cole-Cole
plot) and thereby determines the characteristics of the electrodes
and the electrolyte of the battery cell 42. For example, the ECU 60
determines the SOC and/or SOH of the battery cell 42.
[0075] In addition, it is not necessarily needed to create the
entire Cole-Cole plot. Instead, it is possible to focus on only
part of the Cole-Cole plot. For example, it is possible to: (1)
measure the complex impedance of the battery cell 42 at a specific
frequency at predetermined time intervals during traveling of the
vehicle; and (2) determine changes in the SOC, SOH and temperature
of the battery cell 42 during the traveling based on the change
with time of the complex impedance at the specific frequency.
Alternatively, it is also possible to: (1) measure the complex
impedance of the battery cell 42 at a specific frequency at
predetermined time intervals (e.g., once every day, every week or
every year); and (2) determine the change with time of the SOH of
the battery cell 42 based on the change with time of the complex
impedance at the specific frequency.
[0076] In general, to monitor a state of a battery cell 42, it is
necessary to input/output various signals to/from the battery cell
42. Accordingly, it is necessary to join a plurality of electrical
paths of signals to each electric power supply terminal 71 of the
battery cell 42. Consequently, the time and cost for joining the
electrical paths to the electric power supply terminals 71 of the
battery cell 42 during the assembly of the battery monitoring
apparatus 50 to the battery cell 42 may be increased.
[0077] To solve the above problem, in the present embodiment, the
battery monitoring apparatuses 50 are configured to reduce the
number of electrical paths joined to the electric power supply
terminals 71 of each of the battery cells 42.
[0078] FIG. 4 illustrates the electrical connection between each of
the battery cells 42 and a corresponding one of the battery
monitoring apparatuses 50 according to the present embodiment.
[0079] As shown in FIG. 4, each of the battery cells 42 is shaped
as a thin rectangular cuboid. Moreover, each of the battery cells
42 has its electric power supply terminals 71 (i.e., the
positive-electrode-side and negative-electrode-side electric power
supply terminals 71a and 71b) arranged respectively in opposite end
portions thereof in its longitudinal direction. The battery cells
42 are stacked in a lateral direction thereof (i.e., the vertical
direction in FIG. 4) so as to have their side faces superposed on
one another. More specifically, the battery cells 42 are stacked so
that for each adjacent pair of the battery cells 42, the
positive-electrode-side and negative-electrode-side electric power
supply terminals 71a and 71b of one of the pair of the battery
cells 42 are aligned in the lateral direction respectively with the
negative-electrode-side and positive-electrode-side electric power
supply terminals 71b and 71a of the other of the pair of the
battery cells 42. Consequently, the positive-electrode-side
electric power supply terminals 71a of the battery cells 42 are
arranged alternately with the negative-electrode-side electric
power supply terminals 71b of the battery cells 42 in the lateral
direction.
[0080] Moreover, for each of the battery cells 42, the
positive-electrode-side electric power supply terminal 71a of the
battery cell 42 is connected, via a busbar 73, to the
negative-electrode-side electric power supply terminal 71b of that
one of the battery cells 42 which is located on one lateral side of
and adjacent to the battery cell 42; the negative-electrode-side
electric power supply terminal 71b of the battery cell 42 is
connected, via a busbar 73, to the positive-electrode-side electric
power supply terminal 71a of that one of the battery cells 42 which
is located on the other lateral side of and adjacent to the battery
cell 42. Consequently, all the battery cells 42 are electrically
connected in series with each other via the busbars 73.
[0081] Each of the busbars 73 is formed of an electrically
conductive material and thin plate-shaped. Moreover, each of the
busbars 73 has a length sufficient to connect one adjacent pair of
the electric power supply terminals 71 of the battery cells 42 in
the lateral direction, for example a length approximately twice the
thickness of each of the battery cells 42 in the lateral direction.
Furthermore, each of the busbars 73 is joined (e.g., by welding) to
one adjacent pair of the electric power supply terminals 71 of the
battery cells 42 so as to cover outer end portions (or outer
halves) of the pair of the electric power supply terminals 71 in
the longitudinal direction of the battery cells 42.
[0082] Between the positive-electrode-side electric power supply
terminal 71a and negative-electrode-side electric power supply
terminal 71b of each of the battery cells 42, there is arranged a
flat plate-shaped circuit board 72. The circuit board 72 is
implemented by, for example, a PCB (Printed Circuit Board) or FPC
(Flexible Printed Circuit). On the circuit board 72, electrical
paths (or signal wirings) formed of an electrically conductive
metal extend to connect circuit elements arranged on the circuit
board 72.
[0083] Specifically, the circuit elements arranged (or fixed) on
the circuit board 72 include, for example, the ASIC 50a, the filter
unit 55 and the current modulation circuit 56 of each of the
battery monitoring apparatuses 50. It should be noted that for the
sake of simplicity, in FIG. 4, there are illustrated only the ASIC
50a and current modulation circuit 56 of one of the battery
monitoring apparatuses 50 in detail.
[0084] As shown in FIG. 4, in each of the battery monitoring
apparatuses 50, the positive-electrode-side input terminal 57a,
which is one of the two DC voltage input terminals 57 of the
input/output unit 52 of the ASIC 50a, is connected with a
positive-electrode-side second electrical path 82a. On the circuit
board 72, the second electrical path 82a is formed to extend
straight from the positive-electrode-side input terminal 57a to the
positive-electrode-side electric power supply terminal 71a of the
corresponding battery cell 42. In addition, a battery-cell-side end
portion of the second electrical path 82a is joined, for example by
welding, to the positive-electrode-side electric power supply
terminal 71a of the corresponding battery cell 42.
[0085] On the other hand, the negative-electrode-side input
terminal 57b, which is the other of the two DC voltage input
terminals 57 of the input/output unit 52 of the ASIC 50a, is
connected with a negative-electrode-side second electrical path
82b. On the circuit board 72, the second electrical path 82b is
formed to extend straight from the negative-electrode-side input
terminal 57b to the negative-electrode-side electric power supply
terminal 71b of the corresponding battery cell 42. In addition, a
battery-cell-side end portion of the second electrical path 82b is
joined, for example by welding, to the negative-electrode-side
electric power supply terminal 71b of the corresponding battery
cell 42.
[0086] That is, in the present embodiment, the two DC voltage input
terminals 57 (i.e., 57a and 57b) of the input/output unit 52 of the
ASIC 50a are respectively connected to the two electric power
supply terminals 71 (i.e., 71a and 71b) of the corresponding
battery cell 42 via the two second electrical paths 82 (i.e., 82a
and 82b).
[0087] Moreover, the positive-electrode-side input terminal 58a,
which is one of the two response signal input terminals 58 of the
input/output unit 52 of the ASIC 50a, is connected with a
positive-electrode-side fourth electrical path 84a. On the circuit
board 72, the fourth electrical path 84a is formed to extend
straight from the positive-electrode-side input terminal 58a to the
positive-electrode-side electric power supply terminal 71a of the
corresponding battery cell 42. In addition, a battery-cell-side end
portion of the fourth electrical path 84a is joined, for example by
welding, to the positive-electrode-side electric power supply
terminal 71a of the corresponding battery cell 42.
[0088] On the other hand, the negative-electrode-side input
terminal 58b, which is the other of the two response signal input
terminals 58 of the input/output unit 52 of the ASIC 50a, is
connected with a negative-electrode-side fourth electrical path
84b. On the circuit board 72, the fourth electrical path 84b is
formed to extend straight from the negative-electrode-side input
terminal 58b to the negative-electrode-side electric power supply
terminal 71b of the corresponding battery cell 42. In addition, a
battery-cell-side end portion of the fourth electrical path 84b is
joined, for example by welding, to the negative-electrode-side
electric power supply terminal 71b of the corresponding battery
cell 42.
[0089] That is, in the present embodiment, the two response signal
input terminals 58 (i.e., 58a and 58b) of the input/output unit 52
of the ASIC 50a are respectively connected to the two electric
power supply terminals 71 (i.e., 71a and 71b) of the corresponding
battery cell 42 via the two fourth electrical paths 84 (i.e., 84a
and 84b).
[0090] Moreover, the positive-electrode-side terminal 51a of the
stabilized-electric power supply unit 51 of the ASIC 50a is
connected with a positive-electrode-side first electrical path 81a.
On the other hand, the negative-electrode-side terminal 51b of the
stabilized-electric power supply unit 51 of the ASIC 50a is
connected with a negative-electrode-side first electrical path
81b.
[0091] That is, in the present embodiment, the two terminals 51a
and 51b of the stabilized-electric power supply unit 51 of the ASIC
50a are respectively connected with the two first electrical paths
81 (i.e., 81a and 81b).
[0092] Moreover, a positive-electrode-side terminal 56e of the
current modulation circuit 56 is connected with a
positive-electrode-side third electrical path 83a. In addition, in
the current modulation circuit 56, the positive-electrode-side
terminal 56e is connected to the drain terminal of the
semiconductor switch element 56a (see FIG. 2).
[0093] On the other hand, a negative-electrode-side terminal 56f of
the current modulation circuit 56 is connected with a
negative-electrode-side third electrical path 83b. In addition, in
the current modulation circuit 56, the negative-electrode-side
terminal 56f is connected to the source terminal of the
semiconductor switch element 56a via the resistor 56b (see FIG.
2).
[0094] That is, in the present embodiment, the two terminals 56e
and 56f of the current modulation circuit 56 are respectively
connected with the two third electrical paths 83 (i.e., 83a and
83b).
[0095] The first electrical paths 81 are electrical paths (or
electric power supply lines) through which drive electric power is
supplied from the corresponding battery cell 42 to the battery
monitoring apparatus 50. On the other hand, the third electrical
paths 83 are electrical paths through which the AC signal flows
under constant-current control. The AC signal is considerably
weaker than the DC voltage; thus variation in the AC signal hardly
affects the drive electric power transmitted through the first
electrical paths 81.
[0096] In view of the above, in the present embodiment, the first
electrical paths 81 are respectively merged with the third
electrical paths 83 into fifth electrical paths 85; and the fifth
electrical paths 85 are respectively joined to the electric power
supply terminals 71 of the corresponding battery cell 42.
[0097] More specifically, the positive-electrode-side first
electrical path 81a is merged with the positive-electrode-side
third electrical path 83a into a positive-electrode-side fifth
electrical path 85a; and a battery-cell-side end portion of the
fifth electrical path 85a is joined, for example by welding, to the
positive-electrode-side electric power supply terminal 71a of the
corresponding battery cell 42. On the other hand, the
negative-electrode-side first electrical path 81b is merged with
the negative-electrode-side third electrical path 83b into a
negative-electrode-side fifth electrical path 85b; and a
battery-cell-side end portion of the fifth electrical path 85b is
joined, for example by welding, to the negative-electrode-side
electric power supply terminal 71b of the corresponding battery
cell 42.
[0098] Moreover, in the present embodiment, the first electrical
paths 81 are bent respectively toward the third electrical paths
83, thereby being respectively merged with the third electrical
paths 83. That is, each of the third electrical paths 83 and the
fifth electrical paths 85 is formed to extend straight.
Consequently, the locations at which the electrical paths 82, 84
and 85 are respectively joined to the electric power supply
terminals 71 can be made identical for all the battery cells
42.
[0099] In addition, in the present embodiment, each of the
electrical paths 82, 84 and 85 is directly joined to a
corresponding one of the electric power supply terminals 71 without
any busbar 73 interposed therebetween. More specifically, each of
the electrical paths 82, 84 and 85 has the battery-cell-side end
portion thereof joined (e.g., by welding) to an inner end portion
(or inner half) of a corresponding one of the electric power supply
terminals 71 in the longitudinal direction of the corresponding
battery cell 42.
[0100] According to the present embodiment, it is possible to
achieve the following advantageous effects.
[0101] In each of the battery monitoring apparatuses 50 according
to the present embodiment, the first electrical paths 81 are
respectively merged with the third electrical paths 83 into the
fifth electrical paths 85. Consequently, it becomes possible to
reduce the number of the electrical paths of the battery monitoring
apparatus 50 joined to the electric power supply terminals 71 of
the battery cell 42 that is the monitoring target of the battery
monitoring apparatus 50. As a result, it becomes possible to reduce
the time and cost for joining the electrical paths to the electric
power supply terminals 71 during the assembly of the battery
monitoring apparatus 50 to the battery cell 42.
[0102] In particular, in the present embodiment, the first
electrical paths 81, through which drive electric power is supplied
from the battery cell 42 to the battery monitoring apparatus 50,
are respectively merged with the third electrical paths 83 through
which the weak AC signal flows. The current variation due to the AC
signal is not so large as to affect the drive electric power;
therefore, the current variation does not affect the drive electric
power. Moreover, constant-current control is performed for the AC
signal; therefore, the AC signal is not affected by transmission of
the drive electric power. Accordingly, the merging of the first
electrical paths 81 with the third electrical paths 83 does not
cause the AC signal and the drive electric power to affect each
other.
[0103] On the other hand, the second electrical paths 82 are
provided separately from the first electrical paths 81 and the
third electrical paths 83. Consequently, it becomes possible to
prevent the lengths of the second electrical paths 82 from being
increased due to the merging thereof with other electrical paths.
Thus, it becomes possible to have the DC voltage inputted to the DC
voltage input terminals 57 through the second electrical paths 82
without any additional drop in the DC voltage (i.e., any drop in
the DC voltage due to an additional resistance component). As a
result, it becomes possible for the battery monitoring apparatus 50
to accurately measure the DC voltage. Moreover, the voltage
variation of the drive electric power transmitted through the first
electrical paths 81 tend to become large. Therefore, with the
second electrical paths 82 provided separately from the first
electrical paths 81, it becomes possible to ensure the accuracy of
measurement of the DC voltage by the battery monitoring apparatus
50.
[0104] Moreover, the fourth electrical paths 84 are also provided
separately from the first electrical paths 81 and the third
electrical paths 83. Consequently, it becomes possible to prevent
the lengths of the fourth electrical paths 84 from being increased
due to the merging thereof with other electrical paths. Thus, it
becomes possible to have the response signal inputted to the
response signal input terminals 58 through the fourth electrical
paths 84 without passing through any additional impedance
component. As a result, it becomes possible to ensure the accuracy
of the response signal inputted to the battery monitoring apparatus
50. In particular, the response signal is a very weak signal
whereas variation in the drive electric power transmitted through
the first electrical paths 81 is large. Therefore, with the fourth
electrical paths 84 provided separately from the first electrical
paths 81, it becomes possible to ensure the accuracy of measurement
of the complex impedance of the battery cell 42 by the battery
monitoring apparatus 50.
[0105] In the present embodiment, the battery-cell-side end
portions of the fourth electrical paths 84 are directly joined to
the corresponding electric power supply terminals 71 of the battery
cell 42 without any busbar 73 interposed therebetween.
Consequently, it becomes possible to have the response signal
inputted to the response signal input terminals 58 through the
fourth electrical paths 84 without passing through any additional
impedance component due to a busbar 73. As a result, it becomes
possible to more reliably ensure the accuracy of measurement of the
complex impedance of the battery cell 42 by the battery monitoring
apparatus 50.
[0106] In the present embodiment, the first electrical paths 81 are
bent respectively toward the third electrical paths 83, thereby
being respectively merged with the third electrical paths 83. With
this configuration, the locations at which the electrical paths 82,
84 and 85 are respectively joined to the electric power supply
terminals 71 can be made identical for all the battery cells 42.
Consequently, it becomes possible to facilitate the process of
joining the electrical paths 82, 84 and 85 to the electric power
supply terminals 71 during the assembly of the battery monitoring
apparatuses 50 to the corresponding battery cells 42.
[0107] In the present embodiment, the current modulation circuit 56
is configured to cause the sine-wave signal (or predetermined AC
signal) to be outputted from the battery cell 42 that is the
monitoring target, with the battery cell 42 itself being the
electric power source for the output of the sine-wave signal.
Consequently, it becomes unnecessary to employ an external electric
power source for applying a disturbance to the battery cell 42
(i.e., causing the sine-wave signal to be outputted from the
battery cell 42) for the purpose of measuring the complex impedance
of the battery cell 42. As a result, it becomes possible to reduce
the parts count and the size of the battery monitoring apparatuses
50, thereby lowering the manufacturing cost.
[0108] Moreover, to an in-vehicle storage battery, there are
generally connected peripheral devices such as a protective element
and a filter circuit. Therefore, when an AC signal is inputted as a
disturbance to the storage battery, part of the AC signal may be
leaked to the peripheral devices. For example, in the present
embodiment, to each of the battery cells 42, there are connected
the RC filters 55a and the Zener diode 55b. Therefore, if an AC
signal is inputted to the battery cell 42, part of the AC signal
might be leaked to the RC filters 55a and the Zener diode 55b.
Consequently, if the complex impedance of the battery cell 42 was
calculated based on a response signal of the battery cell 42 to the
inputted AC signal, it might be impossible to ensure the accuracy
of calculation of the complex impedance due to an error in the
response signal caused by the leakage of the AC signal.
[0109] In contrast, in the present embodiment, as described above,
the current modulation circuit 56 is configured to cause the
sine-wave signal to be outputted from the battery cell 42 that is
the monitoring target, with the battery cell 42 itself being the
electric power source for the output of the sine-wave signal.
Consequently, it becomes possible to realize a closed circuit with
the current modulation circuit 56 and the battery cell 42. As a
result, it becomes possible to eliminate current leakage from the
battery cell 42 to the peripheral devices, thereby suppressing
occurrence of an error in the response signal.
[0110] Moreover, a deviation may occur between the current signal
actually flowing through the resistor 56b and the sine-wave signal
desired to be outputted from the battery cell 42; this deviation
may cause an error in the response signal. In view of the above, in
the present embodiment, the current modulation circuit 56 is
configured to include the feedback circuit 56d. The feedback
circuit 56d performs, based on comparison between the feedback
signal (i.e., the detected signal) and the sine-wave signal
commanded by the command signal, a feedback control for the on/off
operation of the semiconductor switch element 56a. Consequently, it
becomes possible to have the commanded (or desired) sine-wave
signal stably and accurately outputted from the battery cell
42.
[0111] In the present embodiment, in commanding the waveform of the
sine-wave signal to the current modulation circuit 56 by the
command signal, the digital-to-analog conversion is performed for
the command signal. However, an error may occur in the waveform of
the command signal during the digital-to-analog conversion. For
suppressing occurrence of such an error, a filter circuit may be
provided between the input/output unit 52 and the current
modulation circuit 56 to smooth the waveform of the command signal.
However, in this case, the size and manufacturing cost of the
battery monitoring apparatus 50 would be increased.
[0112] In particular, the capacity of a vehicular battery cell 42
is generally large. Therefore, the range of measurement frequencies
in calculation (or measurement) of the complex impedance of the
battery cell 42 tends to become wide. Accordingly, if a filter
circuit was provided between the input/output unit 52 and the
current modulation circuit 56 to smooth the waveform of the command
signal, the size of the filter circuit would also become large.
[0113] In contrast, in the present embodiment, as described above,
the feedback circuit 56d performs the feedback control for the
on/off operation of the semiconductor switch element 56a, thereby
suppressing occurrence of an error in the waveform of the command
signal. Consequently, it becomes unnecessary to provide a filter
circuit between the input/output unit 52 and the current modulation
circuit 56.
[0114] In the present embodiment, the current modulation circuit 56
is configured to detect the current signal flowing through the
resistor 56b and output the detected current signal as the feedback
signal to the microcomputer 53 via the input/output unit 52. Then,
the microcomputer 53 calculates the complex impedance of the
battery cell 42 using the feedback signal as the current signal.
Consequently, when there is a deviation (e.g., a phase deviation)
between the current signal actually flowing through the resistor
56b and the sine-wave signal desired to be outputted from the
battery cell 42 (i.e., the sine-wave signal commanded by the
microcomputer 53), it is still possible to ensure the accuracy of
calculation of the complex impedance by using the feedback signal
(i.e., the current signal actually flowing through the resistor
56b).
[0115] Moreover, since the signal correction is performed with the
feedback signal as described above, it becomes unnecessary to
provide a filter circuit between the input/output unit 52 and the
current modulation circuit 56. Consequently, it becomes possible to
minimize the size and manufacturing cost of the battery monitoring
apparatus 50.
[0116] In the present embodiment, the response signal input
terminals 58 are connected respectively to, of all connectable
portions of the electric power supply terminals 71a and 71b of the
battery cell 42, those connectable portions which are located
closest to the electrodes of the battery cell 42. Consequently, it
becomes possible to suppress the influence of impedance components
of the electric power supply terminals 71a and 71b of the battery
cell 42 on the response signal inputted to the battery monitoring
apparatus 50 via the response signal input terminals 58, thereby
improving the accuracy of calculation of the complex impedance of
the battery cell 42.
[0117] More specifically, as illustrated in FIGS. 5A and 5B, the
electric power supply terminals 71a and 71b of the battery cell 42
have impedance components. Therefore, it is preferable for the
response signal input terminals 58 to be connected respectively to
those connectable portions of the electric power supply terminals
71a and 71b which are located closer to the electrodes as shown in
FIG. 5B than those connectable portions which are located further
from the electrodes as shown in FIG. 5A. In addition, as shown in
FIG. 5B, it is preferable that those connectable portions of the
electric power supply terminals 71a and 71b to which the response
signal input terminals 58 are respectively connected are located
closer to the electrodes than those connectable portions to which
the terminals 56e and 56f of the current modulation circuit 56 are
respectively connected are.
[0118] That is, in the present embodiment, the battery-cell-side
end portions of the electrical paths 82, 84 and 85 are respectively
joined to different connectable portions of the electric power
supply terminals 71a and 71b of the battery cell 42. Moreover,
among the different connectable portions of the electric power
supply terminals 71a and 71b, the connectable portions to which the
battery-cell-side end portions of the fourth electrical paths 84
connected with the response signal input terminals 58 are joined
are located closest to the electrodes of the battery cell 42.
Consequently, it becomes possible to suppress the influence of the
impedance components of the electric power supply terminals 71a and
71b on the response signal inputted to the response signal input
terminals 58 through the fourth electrical paths 84, thereby
improving the accuracy of calculation of the complex impedance of
the battery cell 42.
Second Embodiment
[0119] FIG. 6 shows the configuration of a battery monitoring
apparatus 50 according to the second embodiment, which is
configured to perform two-phase lock-in detection on the response
signal.
[0120] As shown in FIG. 6, in the present embodiment, the ASIC 50a
of the battery monitoring apparatus 50 includes a differential
amplifier 151 provided to measure the DC voltage between the
terminals of a battery cell 42 that is the monitoring target.
Specifically, the differential amplifier 151 is connected with the
DC voltage input terminals 57. Moreover, the differential amplifier
151 is configured to measure the DC voltage inputted thereto via
the DC voltage input terminals 57 and output the measured DC
voltage.
[0121] In the present embodiment, the ASIC 50a also includes a
preamplifier 152 provided to input, via the response signal input
terminals 58, voltage variation of the battery cell 42 as the
response signal during the output of the sine-wave signal.
Specifically, the preamplifier 152 is connected with the response
signal input terminals 58. Moreover, the preamplifier 152 is
configured to amplify the voltage variation inputted thereto via
the response signal input terminals 58 and output the amplified
voltage variation as the response signal. That is, the amplitude of
the response signal is considerably lower than the amplitude of the
terminal voltage (i.e., voltage between the terminals) of the
battery cell 42; therefore, the preamplifier 152 is employed to
improve the accuracy of detecting the response signal.
[0122] In addition, in the present embodiment, the preamplifier 152
is implemented by a single-stage amplifier. However, it should be
noted that the preamplifier 152 may alternatively be implemented by
a multi-stage amplifier.
[0123] Moreover, in the present embodiment, as shown in FIG. 6,
between the positive-electrode-side electric power supply terminal
71a of the battery cell 42 and the positive-electrode-side input
terminal 58a which is one of the two the response signal input
terminals 58, there is provided a capacitor C1 to cut off a DC
component of the voltage variation of the battery cell 42.
Consequently, it becomes possible to remove the DC component, which
is irrelevant to the internal complex impedance information of the
battery cell 42, from the voltage variation of the battery cell 42,
thereby improving the accuracy of detecting the response
signal.
[0124] In the present embodiment, the ASIC 50a further includes a
signal switch 153 to select between the DC voltage outputted from
the differential amplifier 151 and the response signal outputted
from the preamplifier 152. Moreover, to the signal switch 153,
there is connected an AD converter 154 to perform an
analog-to-digital conversion for that one of the DC voltage and the
response signal which is selected by the signal switch 153.
[0125] The AD converter 154 is connected with a signal processing
unit 155 that functions as a calculating unit in the second
embodiment. The AD converter 154 is configured to input the DC
voltage to the signal processing unit 155 when the DC voltage is
selected by the signal switch 153. Moreover, the AD converter 154
is also connected with both a first multiplier 156 and a second
multiplier 157. The AD converter 154 is configured to input the
response signal to each of the first and second multipliers 156 and
157 when the response signal is selected by the signal switch
153.
[0126] To the first multiplier 156, there is connected an
oscillating circuit 158 which will be described later. A first
reference signal is inputted from oscillating circuit 158 to the
first multiplier 156. Then, the first multiplier 156 calculates a
value proportional to the real part of the response signal by
multiplying the first reference signal and the response signal
together. Thereafter, the first multiplier 156 outputs the value
proportional to the real part of the response signal to the signal
processing unit 155 via a low-pass filter 159. In addition, in FIG.
6, the real part of the response signal is denoted by Re|Vr|.
[0127] To the second multiplier 157, there is connected the
oscillating circuit 158 via a phase-shift circuit 160. A second
reference signal is inputted from the phase-shift circuit 160 to
the second multiplier 157; the second reference signal is produced
by the phase-shift circuit 160 by advancing the phase of the first
reference signal by 90.degree. (i.e., .pi./2). More specifically,
the phase-shift circuit 160 is configured to advance the phase of a
sine-wave signal (i.e., the first reference signal) inputted
thereto from the oscillating circuit 158 and output the
phase-advanced sine-wave signal as the second reference signal to
the second multiplier 157.
[0128] The second multiplier 157 calculates a value proportional to
the imaginary part of the response signal by multiplying the second
reference signal and the response signal together. Then, the second
multiplier 157 outputs the value proportional to the imaginary part
of the response signal to the signal processing unit 155 via a
low-pass filter 161. In addition, in FIG. 6, the imaginary part of
the response signal is denoted by Im|Vr|.
[0129] The oscillating circuit 158 is configured to output the
predetermined sine-wave single and functions as a waveform
commanding unit. As described above, the oscillating circuit 158
outputs the sine-wave signal as the first reference signal to both
the first multiplier 156 and the phase-shift circuit 160. Moreover,
the oscillating circuit 158 is connected with the command signal
output terminal 59a via a DA converter 162. The oscillating circuit
158 outputs the sine-wave signal as the command signal to the
command signal output terminal 59a through the digital-to-analog
conversion by the DA converter 162.
[0130] The feedback signal input terminal 59b is connected with the
signal processing unit 155 via an AD converter 163. The feedback
signal (or detected signal) is inputted from the feedback signal
input terminal 59b to the signal processing unit 155 through the
analog-to-digital conversion by the AD converter 163.
[0131] The signal processing unit 155 receives both the value
proportional to the real part of the response signal and the value
proportional to the imaginary part of the response signal. Then,
based on these values, the signal processing unit 155 calculates
both the real and imaginary parts of the complex impedance of the
battery cell 42. Moreover, based on the feedback signal inputted
thereto, the signal processing unit 155 corrects both the real and
imaginary parts of the complex impedance taking into account the
amplitude of the current signal actually flowing through the
resistor 56b and the phase difference of the current signal from
the sine-wave signal commanded by the command signal.
[0132] Furthermore, the signal processing unit 155 also calculates
both the absolute value and the phase of the complex impedance.
More specifically, since both the real part and the imaginary part
of the response signal have been detected by the two-phase lock-in
detection, the response signal can be represented by
|Vr|e{circumflex over ( )}j.theta.v in polar coordinates on a
complex plane, where .theta.v is the phase of the response signal.
Similarly, the current can be represented by |I|e{circumflex over (
)}j.theta.i in polar coordinates on the complex plane, where
.theta.i is the phase of the current. Moreover, the complex
impedance of the battery cell 42 can be represented by
|Z|e{circumflex over ( )}j.theta.z in polar coordinates on the
complex plane, where .theta.z is the phase of the complex
impedance. Then, the following equation (1) can be derived from
V=ZI. In addition, "j" is the imaginary unit satisfying
(j{circumflex over ( )}2=-1).
Z e j .theta. z = Vr e j .theta. v I e j .theta. i ( 1 )
##EQU00001##
[0133] The signal processing unit 155 calculates the absolute value
of the complex impedance by (|Z|=|Vr|/|I|). Moreover, the signal
processing unit 155 calculates the phase of the complex impedance
by (.theta.v-.theta.i). Thereafter, the signal processing unit 155
outputs the calculation results to the ECU 60 via the communication
unit 54. In addition, in FIG. 6, the absolute value and the phase
of the complex impedance are respectively denoted by |Z| and
arg(Z).
[0134] Next, a process of calculating the complex impedance of a
battery cell 42 according to the second embodiment will be
described with reference to FIG. 7. This process is repeatedly
performed by the battery monitoring apparatus 50 in a predetermined
cycle.
[0135] In the complex impedance calculating process, first, in step
S201, the oscillating circuit 158 sets a measurement frequency of
the complex impedance within a predetermined frequency range. In
addition, in the second embodiment, the measurement frequency is
determined by, for example, the signal processing unit 155.
[0136] In step S202, the signal switch 153 is set to allow, of the
DC voltage outputted from the differential amplifier 151 and the
response signal outputted from the preamplifier 152, only the
response signal to be outputted to the AD converter 154. In
addition, the signal switch 153 is operated according to, for
example, a command from the signal processing unit 155.
[0137] In step S203, the oscillating circuit 158 sets the frequency
of the sine-wave signal (or predetermined AC signal) based on the
measurement frequency set in step S201. Then, the oscillating
circuit 158 outputs the command signal, through the
digital-to-analog conversion by the DA converter 162, to the
current modulation circuit 56 via the command signal output
terminal 59a. As described previously, the command signal is
indicative of a command commanding the current modulation circuit
56 to cause the sine-wave signal to be outputted from the battery
cell 42. In addition, the oscillating circuit 158 outputs the
command signal according to, for example, a command from the signal
processing unit 155.
[0138] In the digital-to-analog conversion of the command signal by
the DA converter 162, a suitable offset value (i.e., DC bias) is
set taking into account the DC voltage of the battery cell 42. More
specifically, the offset value is set by, for example, the signal
processing unit 155. Moreover, it is desirable for the offset value
to be set based on the DC voltage of the battery cell 42. In
addition, the DC voltage of the battery cell 42 may be measured by
the differential amplifier 151.
[0139] In step S204, according to the command signal, the current
modulation circuit 56 causes the sine-wave signal to be outputted
from the battery cell 42 that is the monitoring target, with the
battery cell 42 itself being the electric power source for the
output of the sine-wave signal. Consequently, the sine-wave signal
is outputted from the battery cell 42.
[0140] Upon the sine-wave signal being outputted from the battery
cell 42, in other words, upon application of a disturbance to the
battery cell 42, variation occurs in the voltage between the
terminals of the battery cell 42; the voltage variation is
indicative of the internal complex impedance information of the
battery cell 42. Then, the preamplifier 152 outputs, as the
response signal, the voltage variation which is inputted to the
preamplifier 152 via the response signal input terminals 58.
[0141] In addition, during the input of the voltage variation from
the battery cell 42 to the response signal input terminals 58, the
DC component of the voltage variation is cut off (or removed) by
the capacitor C1, leaving only the characterizing part of the
voltage variation. It is desirable for the size of the DC component
cut off by the capacitor C1 to be adjusted based on the DC voltage
of the battery cell 42. The preamplifier 152 amplifies the weak
voltage variation from which the DC component has been removed, and
outputs the amplified voltage variation as the response signal. It
is desirable for the degree of amplification of the voltage
variation by the preamplifier 152 to be adjusted based on the DC
voltage of the battery cell 42.
[0142] The AD converter 154 performs the analog-to-digital
conversion on the response signal which is inputted to the AD
converter 154 via the signal switch 153. Then, the AD converter 154
outputs the response signal in a digital form to each of the first
and second multipliers 156 and 157.
[0143] In step S205, each of the first and second multipliers 156
and 157 receives the response signal outputted from the AD
converter 154.
[0144] In step S206, the first multiplier 156 calculates a value
proportional to the real part of the response signal by multiplying
the first reference signal (i.e., the sine-wave signal from the
oscillating circuit 158) and the response signal together. At the
same time, the second multiplier 157 calculates a value
proportional to the imaginary part of the response signal by
multiplying the second reference signal (i.e., the phase-advanced
sine-wave signal from the phase-shift circuit 160) and the response
signal together.
[0145] Then, the values calculated by the first and second
multipliers 156 and 157 are inputted to the signal processing unit
155 respectively through the low-pass filters 159 and 161. In
addition, when passing through the low-pass filters 159 and 161,
signal components other than DC components are attenuated (or
removed).
[0146] In step S207, the signal processing unit 155 acquires the
feedback signal (or detected signal) from the feedback signal input
terminal 59b. More specifically, the feedback signal is inputted
from the feedback signal input terminal 59b to the signal
processing unit 155 through the analog-to-digital conversion by the
AD converter 163.
[0147] In step S208, the signal processing unit 155 calculates,
based on the feedback signal and the signals (or values
respectively proportional to the real and imaginary parts of the
response signal) from the low-pass filters 159 and 161, at least
one of the real part, the imaginary part, the absolute value and
the phase of the complex impedance of the battery cell 42. In
addition, the feedback signal is used to correct (or eliminate) any
deviation in amplitude or phase between the current signal actually
outputted from the battery cell 42 and the sine-wave signal desired
to be outputted from the battery cell 42.
[0148] In step S209, the signal processing unit 155 outputs the
calculation results to the ECU 60 via the communication unit 54.
Then, the complex impedance calculating process terminates.
[0149] The above calculating process is repeated until the complex
impedance of the battery cell 42 has been calculated with respect
to a plurality of measurement frequencies within the predetermined
frequency range. Based on the calculation results, the ECU 60
creates, for example, a complex impedance plane plot (or Cole-Cole
plot) and thereby determines the characteristics of the electrodes
and the electrolyte of the battery cell 42. For example, the ECU 60
determines the SOC and/or SOH of the battery cell 42.
[0150] In addition, it is not necessarily needed to create the
entire Cole-Cole plot. Instead, it is possible to focus on only
part of the Cole-Cole plot. For example, it is possible to: (1)
measure the complex impedance of the battery cell 42 at a specific
frequency at predetermined time intervals during traveling of the
vehicle; and (2) determine changes in the SOC, SOH and temperature
of the battery cell 42 during the traveling based on the change
with time of the complex impedance at the specific frequency.
Alternatively, it is also possible to: (1) measure the complex
impedance of the battery cell 42 at a specific frequency at
predetermined time intervals (e.g., once every day, every week or
every year); and (2) determine the change with time of the SOH of
the battery cell 42 based on the change with time of the complex
impedance at the specific frequency.
[0151] In addition, in the second embodiment, the battery cell 42
and the battery monitoring apparatus 50 are connected in the same
manner as in the first embodiment. Moreover, the electrical paths
81-85 are formed on the circuit board 72 in the same manner as in
the first embodiment. Therefore, descriptions of the connection
between the battery cell 42 and the battery monitoring apparatus 50
and the formation of the electrical paths 81-85 on the circuit
board 72 are not repeated hereinafter.
[0152] According to the second embodiment, it is possible to
achieve the following advantageous effects.
[0153] In the battery monitoring apparatus 50 according to the
present embodiment, the signal processing unit 155 calculates a
value proportional to the real part of the response signal based on
the product of the response signal inputted via the response signal
input terminals 58 and the first reference signal together.
Moreover, the signal processing unit 155 also calculates a value
proportional to the imaginary part of the response signal based on
the product of the response signal and the second reference signal
that is produced by shifting the phase of the sine-wave signal
(i.e., the first reference signal). Then, the signal processing
unit 155 calculates the complex impedance of the battery cell 42
based on the above values. Consequently, by performing the
so-called lock-in detection, it becomes possible to extract, from
the response signal, only a component having the same frequency as
the sine-wave signal commanded by the oscillating circuit 158.
Therefore, the battery monitoring apparatus 50 according to the
present embodiment is tolerant to white noise and pink noise and
capable of accurately calculating the complex impedance of the
battery cell 42. Accordingly, the battery monitoring apparatus 50
according to the present embodiment is particularly suitable for
use in a vehicle where there are generally present various types of
noise. Moreover, since the battery monitoring apparatus 50 is
tolerant to noise, it becomes possible to lower the current (i.e.,
the sine-wave signal) caused to be outputted from the battery cell
42. Consequently, it becomes possible to suppress consumption of
the electric power of the battery cell 42; it also becomes possible
to suppress increase in the temperatures of the battery cell 42 and
the semiconductor switch element 56a of the battery monitoring
apparatus 50.
[0154] Moreover, in the present embodiment, the signal processing
unit 155 acquires, from the current modulation circuit 56, the
feedback signal that is the detected current signal actually
outputted from (or actually flowing out of) the battery cell 42.
Then, the signal processing unit 155 corrects (or eliminates) any
deviation in amplitude or phase between the current signal actually
outputted from the battery cell 42 and the sine-wave signal
commanded by the command signal. Consequently, it becomes possible
to improve the accuracy of calculation of the complex impedance of
the battery cell 42.
[0155] Furthermore, in the present embodiment, even if an error
occurs in the waveform of the command signal during the
digital-to-analog conversion by the DA converter 162, it is
possible to suppress the error by the correction performed using
the feedback signal. Consequently, it becomes unnecessary to
provide a filter circuit between the current modulation circuit 56
and the DA converter 162. As a result, it becomes possible to
minimize the size and manufacturing cost of the battery monitoring
apparatus 50.
Third Embodiment
[0156] FIG. 8 shows the configuration of a battery monitoring
apparatus 50 according to the third embodiment, which is configured
to perform a FFT (Fast Fourier Transform) in signal analyses.
[0157] As shown in FIG. 8, in the present embodiment, the ASIC 50a
of the battery monitoring apparatus 50 includes a signal processing
unit 201 that functions as a calculating unit to perform the FFT.
The signal processing unit 201 is configured to receive the
measurement value of the DC voltage of the battery cell 42 via the
AD converter 154. Moreover, the signal processing unit 201 is also
configured to receive the response signal via the AD converter 154.
Furthermore, the signal processing unit 201 is also configured to
receive the feedback signal via the AD converter 163. In addition,
the signal processing unit 201 is connected with the oscillating
circuit 158 and configured to be capable of setting the frequency
of the sine-wave signal.
[0158] In the present embodiment, the signal processing unit 201
performs the FFT on each of the response signal (i.e., voltage
signal) and the feedback signal (i.e., current signal). Then, the
signal processing unit 201 calculates the real part, the imaginary
part, the absolute value and the phase of the complex impedance of
the battery cell 42 on the basis of the results of performing the
FFT on the response signal and the feedback signal. Thereafter, the
signal processing unit 201 outputs the calculation results to the
ECU 60 via the communication unit 54.
[0159] Next, a process of calculating the complex impedance of a
battery cell 42 according to the third embodiment will be described
with reference to FIG. 9. This process is repeatedly performed by
the battery monitoring apparatus 50 in a predetermined cycle.
[0160] Steps S301-S305 of the complex impedance calculating process
according to the third embodiment are respectively identical to
steps S201-S205 of the complex impedance calculating process
according to the second embodiment. Therefore, descriptions of
steps S301-S305 of the complex impedance calculating process
according to the third embodiment are omitted hereinafter.
[0161] In addition, in the third embodiment, the measurement
frequency and the offset value (i.e., DC bias) are set by the
signal processing unit 201. Moreover, operation of the signal
switch 153 and output of the command signal are commanded (or
controlled) by the signal processing unit 201.
[0162] In step S306 of the complex impedance calculating process
according to the third embodiment, the signal processing unit 201
performs the FFT on the response signal received from the AD
converter 154. Consequently, information on the amplitude of the
response signal with respect to the measurement frequency is
obtained.
[0163] In step S307, the signal processing unit 201 acquires the
feedback signal from the feedback signal input terminal 59b. More
specifically, the feedback signal is inputted from the feedback
signal input terminal 59b to the signal processing unit 201 through
the analog-to-digital conversion by the AD converter 163.
[0164] In step S308, the signal processing unit 201 performs the
FFT on the feedback signal. Consequently, information on the
amplitude of the feedback signal with respect to the measurement
frequency is obtained.
[0165] In step S309, the signal processing unit 201 calculates,
based on both the amplitude information of the response signal
obtained in step S306 and the amplitude information of the feedback
signal obtained in step S308, at least one of the real part, the
imaginary part, the absolute value and the phase of the complex
impedance of the battery cell 42.
[0166] In step S310, the signal processing unit 201 outputs the
calculation results to the ECU 60 via the communication unit 54.
Then, the complex impedance calculating process terminates.
[0167] The above calculating process is repeated until the complex
impedance of the battery cell 42 has been calculated with respect
to a plurality of measurement frequencies within the predetermined
frequency range. Based on the calculation results, the ECU 60
creates, for example, a complex impedance plane plot (or Cole-Cole
plot) and thereby determines the characteristics of the electrodes
and the electrolyte of the battery cell 42. For example, the ECU 60
determines the SOC and/or SOH of the battery cell 42.
[0168] In addition, it is not necessarily needed to create the
entire Cole-Cole plot. Instead, it is possible to focus on only
part of the Cole-Cole plot. For example, it is possible to: (1)
measure the complex impedance of the battery cell 42 at a specific
frequency at predetermined time intervals during traveling of the
vehicle; and (2) determine changes in the SOC, SOH and temperature
of the battery cell 42 during the traveling based on the change
with time of the complex impedance at the specific frequency.
Alternatively, it is also possible to: (1) measure the complex
impedance of the battery cell 42 at a specific frequency at
predetermined time intervals (e.g., once every day, every week or
every year); and (2) determine the change with time of the SOH of
the battery cell 42 based on the change with time of the complex
impedance at the specific frequency.
[0169] In addition, in the third embodiment, the battery cell 42
and the battery monitoring apparatus 50 are connected in the same
manner as in the first embodiment. Moreover, the electrical paths
81-85 are formed on the circuit board 72 in the same manner as in
the first embodiment. Therefore, descriptions of the connection
between the battery cell 42 and the battery monitoring apparatus 50
and the formation of the electrical paths 81-85 on the circuit
board 72 are not repeated hereinafter.
[0170] According to the third embodiment, it is possible to achieve
the following advantageous effects.
[0171] In the battery monitoring apparatus 50 according to the
present embodiment, the signal processing unit 201 performs the FFT
on each of the response signal and the feedback signal, thereby
obtaining not only the amplitude information and phase information
of both the response and feedback signals (i.e., voltage and
current signals) with respect to the measurement frequency but also
the amplitude information and phase information of both the
response and feedback signals with respect to harmonics of the
measurement frequency. Consequently, it becomes possible to
calculate the complex impedance of the battery cell 42 with respect
to a plurality of frequencies at one time.
[0172] Moreover, in the present embodiment, the signal processing
unit 201 acquires, from the current modulation circuit 56, the
feedback signal that is the detected current signal actually
outputted from (or actually flowing out of) the battery cell 42.
Then, the signal processing unit 201 performs the FFT on the
feedback signal. Consequently, it becomes possible to correct (or
eliminate) any deviation in amplitude or phase between the current
signal actually outputted from the battery cell 42 and the
sine-wave signal commanded by the command signal. As a result, it
becomes possible to improve the accuracy of calculation of the
complex impedance of the battery cell 42.
Fourth Embodiment
[0173] As described above, in the first embodiment, each battery
monitoring apparatus 50 is configured to monitor one battery cell
42. Alternatively, each battery monitoring apparatus 50 may be
configured to monitor a plurality of battery cells 42 (e.g., all
the battery cells 42 of one battery module 41 or all the battery
cells 42 of the entire battery pack 40). Moreover, some functions
of the battery monitoring apparatus 50 may be shared by all the
battery cells 42.
[0174] FIG. 10 shows the configuration of a battery monitoring
apparatus 50 according to the fourth embodiment.
[0175] As shown in FIG. 10, in the present embodiment, the
stabilized-electric power supply unit 301, the communication unit
54 and the microcomputer 53 of the battery monitoring apparatus 50
are shared by all the battery cells 42 of the battery pack 40 (or
of one battery module 41).
[0176] Moreover, the electric potentials of the negative electrodes
of the battery cells 42 are different from each other. Accordingly,
the reference electric potentials of the battery cells 42 for
various electrical signals used to communicate various types of
information are also different from each other. Therefore, it is
necessary to have the various electrical signals from the battery
cells 42 inputted to the microcomputer 53 and processed by the
microcomputer 53 taking into account the differences between the
reference electric potentials. In addition, as means for
communicating signals between different reference electric
potentials, a capacitor, a transformer, a radio wave and/or light
may be employed.
[0177] In the present embodiment, as shown in FIG. 10, the
stabilized-electric power supply unit 301 is configured to be
supplied with the terminal voltage (or voltage between the
terminals) of the battery pack 40 (or one battery module 41). That
is, the stabilized-electric power supply unit 301 is connected
with: (1) the positive-electrode-side electric power supply
terminal 71a of that one of all the battery cells 42 of the battery
pack 40 (or of one battery module 41) which has the highest
electric potential in the battery pack 40 (or in the battery module
41); and (2) the negative-electrode-side electric power supply
terminal 71b of that one of all the battery cells 42 of the battery
pack 40 (or of one battery module 41) which has the lowest electric
potential in the battery pack 40 (or in the battery module 41).
[0178] Accordingly, in the present embodiment, of all the battery
cells 42 of the battery pack 40 (or of one battery module 41), only
the two battery cells 42 arranged respectively at opposite ends of
the battery pack 40 (or the battery module 41) in the series
connection direction (or stacking direction) of the battery cells
42 have electrical paths formed to be different from the electrical
paths of the other battery cells 42.
[0179] Specifically, as shown in FIG. 11, to the
positive-electrode-side electric power supply terminal 71a of the
battery cell 42 arranged at the higher-potential-side end (i.e.,
the upper end in FIG. 11) of the battery pack 40 in the series
connection direction, there is connected a positive-electrode-side
fifth electrical path 85a. The positive-electrode-side fifth
electrical path 85a is branched into a positive-electrode-side
first electrical path 81a and a positive-electrode-side third
electrical path 83a. The positive-electrode-side first electrical
path 81a, which is shown with a one-dot chain line in FIG. 11, is
connected with a positive-electrode-side terminal 301a of the
stabilized-electric power supply unit 301. The
positive-electrode-side third electrical path 83a is connected with
the positive-electrode-side terminal 56e of the current modulation
circuit 56 corresponding to the battery cell 42 arranged at the
higher-potential-side end of the battery pack 40.
[0180] Moreover, no negative-electrode-side fifth electrical path
85b is connected to the negative-electrode-side electric power
supply terminal 71b of the battery cell 42 arranged at the
higher-potential-side end of the battery pack 40. Instead, the
negative-electrode-side terminal 56f of the current modulation
circuit 56 corresponding to the battery cell 42 is connected to the
negative-electrode-side electric power supply terminal 71b of the
battery cell 42 via the negative-electrode-side third electrical
path 83b. In addition, the second electrical paths 82 corresponding
to the battery cell 42 are connected to the ASIC 50a separately
from the fourth electrical paths 84 corresponding to the battery
cell 42.
[0181] On the other hand, to the negative-electrode-side electric
power supply terminal 71b of the battery cell 42 arranged at the
lower-potential-side end (i.e., the lower end in FIG. 11) of the
battery pack 40 in the series connection direction, there is
connected a negative-electrode-side fifth electrical path 85b. The
negative-electrode-side fifth electrical path 85b is branched into
a negative-electrode-side first electrical path 81b and a
negative-electrode-side third electrical path 83b. The
negative-electrode-side first electrical path 81b, which is shown
with a one-dot chain line in FIG. 11, is connected with a
negative-electrode-side terminal 301b of the stabilized-electric
power supply unit 301. The negative-electrode-side third electrical
path 83b is connected with the negative-electrode-side terminal 56f
of the current modulation circuit 56 corresponding to the battery
cell 42 arranged at the lower-potential-side end of the battery
pack 40.
[0182] Moreover, no positive-electrode-side fifth electrical path
85a is connected to the positive-electrode-side electric power
supply terminal 71a of the battery cell 42 arranged at the
lower-potential-side end of the battery pack 40. Instead, the
positive-electrode-side terminal 56e of the current modulation
circuit 56 corresponding to the battery cell 42 is connected to the
positive-electrode-side electric power supply terminal 71a of the
battery cell 42 via the positive-electrode-side third electrical
path 83a. In addition, the second electrical paths 82 corresponding
to the battery cell 42 are connected to the ASIC 50a separately
from the fourth electrical paths 84 corresponding to the battery
cell 42.
[0183] Each of the battery cells 42 other than those arranged at
the ends of the battery pack 40 has no fifth electrical paths 85
and thus no first electrical paths 81 connected to the electric
power supply terminals 71 thereof. Instead, each of the battery
cells 42 other than those arranged at the ends of the battery pack
40 has: a positive-electrode-side third electrical path 83a
connected with the positive-electrode-side electric power supply
terminal 71a thereof; and a negative-electrode-side third
electrical path 83b connected with the negative-electrode-side
electric power supply terminal 71b thereof. In addition, the second
electrical paths 82 corresponding to the battery cells 42 are
connected to the ASIC 50a separately from the fourth electrical
paths 84 corresponding to the battery cells 42.
[0184] As above, in the present embodiment, each of the electric
power supply terminals 71 of the battery cells 42 has only three
electrical paths joined thereto. Moreover, the first electrical
paths 81 are bent respectively toward the third electrical paths
83, thereby being respectively merged with the third electrical
paths 83. Consequently, the locations at which the electrical paths
are respectively joined to the electric power supply terminals 71
can be made identical for all the battery cells 42. As a result, it
becomes possible to facilitate the process of joining the
electrical paths to the electric power supply terminals 71 during
the assembly of the battery monitoring apparatus 50 to the battery
cells 42.
Fifth Embodiment
[0185] As described above, in the second embodiment, each battery
monitoring apparatus 50 is configured to monitor one battery cell
42. Alternatively, each battery monitoring apparatus 50 may be
configured to monitor a plurality of battery cells 42 (e.g., all
the battery cells 42 of one battery module 41 or all the battery
cells 42 of the entire battery pack 40). Moreover, some functions
of the battery monitoring apparatus 50 may be shared by all the
battery cells 42.
[0186] FIG. 12 shows the configuration of a battery monitoring
apparatus 50 according to the fifth embodiment.
[0187] As shown in FIG. 12, in the present embodiment, the
stabilized-electric power supply unit 301, the communication unit
54, the differential amplifier 151, the preamplifier 152, the
signal switch 153, the AD converters 154 and 163, the signal
processing unit 155, the first multiplier 156, the second
multiplier 157, the low-pass filters 159 and 161, the oscillating
circuit 158, the phase-shift circuit 160, the DA converter 162, the
feedback circuit 56d and the current detection amplifier 56c are
shared by all the battery cells 42 of the battery pack 40 (or of
one battery module 41).
[0188] Moreover, in the present embodiment, multiplexers 302-304
are employed to perform switching of various signals, such as the
DC voltage, the response signal and the command signal, between the
battery cells 42. In addition, the multiplexers 302-304 are
controlled by, for example, the signal processing unit 155.
[0189] Next, the electrical connection between the battery cells 42
and the battery monitoring apparatus 50 according to the present
embodiment will be described with reference to FIG. 13.
[0190] In the present embodiment, as shown in FIG. 13, each of the
electric power supply terminals 71 of the battery cells 42 is
connected with the corresponding electrical paths via the
corresponding busbar 73. It should be noted that for the sake of
simplicity, the second electrical paths 82 and the fourth
electrical paths 84, which are formed in the same manner as in the
second embodiment, are not shown in FIG. 13.
[0191] In the present embodiment, the third electrical paths 83 of
the adjacent (or serially-connected) battery cells 42 are merged in
pairs. Specifically, as shown in FIG. 13, the battery cells 42 are
stacked in a lateral direction thereof (i.e., the vertical
direction in FIG. 13) so that for each adjacent pair of the battery
cells 42, the positive-electrode-side and negative-electrode-side
electric power supply terminals 71a and 71b of one of the pair of
the battery cells 42 are aligned in the lateral direction
respectively with the negative-electrode-side and
positive-electrode-side electric power supply terminals 71b and 71a
of the other of the pair of the battery cells 42. Consequently, the
positive-electrode-side electric power supply terminals 71a of the
battery cells 42 are arranged alternately with the
negative-electrode-side electric power supply terminals 71b of the
battery cells 42 in the lateral direction. Moreover, for each of
the battery cells 42, the positive-electrode-side electric power
supply terminal 71a of the battery cell 42 is connected, via a
busbar 73, to the negative-electrode-side electric power supply
terminal 71b of that one of the battery cells 42 which is located
on one lateral side of and adjacent to the battery cell 42; and the
negative-electrode-side electric power supply terminal 71b of the
battery cell 42 is connected, via a busbar 73, to the
positive-electrode-side electric power supply terminal 71a of that
one of the battery cells 42 which is located on the other lateral
side of and adjacent to the battery cell 42. Consequently, all the
battery cells 42 are electrically connected in series with each
other via the busbars 73.
[0192] In addition, each of the busbars 73 is formed to extend in
the lateral direction so as to connect one adjacent pair of the
positive-electrode-side and negative-electrode-side electric power
supply terminals 71a and 71b of the battery cells 42.
[0193] For the sake of convenience of explanation, the four battery
cells 42 shown in FIG. 13 are sequentially numbered from the upper
side as the first battery cell 421, the second battery cell 422,
the third battery cell 423 and the fourth battery cell 424.
Moreover, hereinafter, the current modulation circuit 56 configured
to cause the sine-wave signal to be outputted from the first
battery cell 421 will be referred to as the first current
modulation circuit 561; the current modulation circuit 56
configured to cause the sine-wave signal to be outputted from the
second battery cell 422 will be referred to as the second current
modulation circuit 562; the current modulation circuit 56
configured to cause the sine-wave signal to be outputted from the
third battery cell 423 will be referred to as the third current
modulation circuit 563; and the current modulation circuit 56
configured to cause the sine-wave signal to be outputted from the
fourth battery cell 424 will be referred to as the fourth current
modulation circuit 564.
[0194] As shown in FIG. 13, the negative-electrode-side electric
power supply terminal 71b of the first battery cell 421 is
connected, via a busbar 73, to the positive-electrode-side electric
power supply terminal 71a of the second battery cell 422. Moreover,
the negative-electrode-side electric power supply terminal 71b of
the second battery cell 422 is connected, via a busbar 73, to the
positive-electrode-side electric power supply terminal 71a of the
third battery cell 423. The negative-electrode-side electric power
supply terminal 71b of the third battery cell 423 is connected, via
a busbar 73, to the positive-electrode-side electric power supply
terminal 71a of the fourth battery cell 424. The remaining electric
power supply terminals 71 of the battery cells 42 are also
connected in the same manner as those of the above-described first
to fourth battery cells 421-424.
[0195] Moreover, as shown in FIG. 13, to the
negative-electrode-side terminal 56f of the first current
modulation circuit 561, there is connected a
negative-electrode-side third electrical path 83b. The
negative-electrode-side third electrical path 83b is bent toward a
positive-electrode-side third electrical path 83a that is connected
with the positive-electrode-side terminal 56e of the second current
modulation circuit 562, thereby being merged with the
positive-electrode-side third electrical path 83a into an
electrical path; the electrical path is connected to the busbar 73
that connects the negative-electrode-side electric power supply
terminal 71b of the first battery cell 421 and the
positive-electrode-side electric power supply terminal 71a of the
second battery cell 422.
[0196] That is, the negative-electrode-side third electrical path
83b extending from the first current modulation circuit 561 is
connected to the negative-electrode-side electric power supply
terminal 71b of the first battery cell 421 via the busbar 73.
Similarly, the positive-electrode-side third electrical path 83a
extending from the second current modulation circuit 562 is
connected to the positive-electrode-side electric power supply
terminal 71a of the second battery cell 422 via the busbar 73.
[0197] In the present embodiment, the multiplexers 302-304 are
controlled by the signal processing unit 155 so as to allow signals
to be inputted to and outputted from only one of the battery cells
42 which is selected as a monitoring target. For example, when the
first battery cell 421 is selected as a monitoring target, the
multiplexers 302-304 are controlled so as to: cause the sine-wave
signal (or predetermined AC signal) to be outputted from only the
first battery cell 421; and allow only the response signal of the
first battery cell 421 to be inputted to the preamplifier 152.
[0198] Therefore, though the negative-electrode-side third
electrical path 83b extending from the first current modulation
circuit 561 is merged with the positive-electrode-side third
electrical path 83a extending from the second current modulation
circuit 562, operation of the first current modulation circuit 561
for causing the sine-wave signal to be outputted from the first
battery cell 421 is prevented from being affected by the second
battery cell 422. Similarly, when the second battery cell 422 is
selected as a monitoring target, operation of the second current
modulation circuit 562 for causing the sine-wave signal to be
outputted from the second battery cell 422 is prevented from being
affected by the first battery cell 421.
[0199] As above, in the present embodiment, each corresponding pair
of the third electrical paths 83 provided respectively for the
adjacent battery cells 42 are merged with each other. Consequently,
it becomes possible to further reduce the number of the electrical
paths joined to each of the electric power supply terminals 71 of
the battery cells 42.
[0200] In addition, in the present embodiment, it is undesirable
for the third electrical paths 83 to be merged with the second
electrical paths 82 or with the fourth electrical paths 84. In
other words, it is desirable for the third electrical paths 83 to
be provided separately from the second electrical paths 82 and the
fourth electrical paths 84. This is because if the third electrical
paths 83 were merged with the second electrical paths 82 or with
the fourth electrical paths 84, the lengths of the third electrical
paths 83 to the electric power supply terminals 71 of the battery
cells 42 would be increased and thus errors might occur due to
additional resistance components (or impedance components).
[0201] On the other hand, the first electrical paths 81 may be
either merged with the third electrical paths 83 or provided
separately from the third electrical paths 83.
[0202] In addition, in the present embodiment, the current
modulation circuits 56 may be supplied with drive electric power
respectively by the battery cells 42 as in the first embodiment. In
this case, the first electrical paths 81 may be merged with the
third electrical paths 83 as in the first embodiment.
Sixth Embodiment
[0203] As described above, in the third embodiment, each battery
monitoring apparatus 50 is configured to monitor one battery cell
42. Alternatively, each battery monitoring apparatus 50 may be
configured to monitor a plurality of battery cells 42 (e.g., all
the battery cells 42 of one battery module 41 or all the battery
cells 42 of the entire battery pack 40). Moreover, some functions
of the battery monitoring apparatus 50 may be shared by all the
battery cells 42.
[0204] FIG. 14 shows the configuration of a battery monitoring
apparatus 50 according to the sixth embodiment.
[0205] As shown in FIG. 14, in the present embodiment, the
stabilized-electric power supply unit 301, the communication unit
54, the differential amplifier 151, the preamplifier 152, the
signal switch 153, the AD converters 154 and 163, the signal
processing unit 201, the oscillating circuit 158, the DA converter
162, the feedback circuit 56d and the current detection amplifier
56c are shared by all the battery cells 42 of the battery pack 40
(or of one battery module 41).
[0206] Moreover, in the present embodiment, multiplexers 302-304
are employed to perform switching of various signals, such as the
DC voltage, the response signal and the command signal, between the
battery cells 42. In addition, the multiplexers 302-304 are
controlled by, for example, the signal processing unit 201.
[0207] In the sixth embodiment, the battery cells 42 and the
battery monitoring apparatus 50 are connected in the same manner as
in the fourth embodiment or the fifth embodiment. Therefore,
description of the connection between the battery cells 42 and the
battery monitoring apparatus 50 is not repeated hereinafter.
[0208] While the above particular embodiments have been shown and
described, it will be understood by those skilled in the art that
various modifications, changes and improvements may be made without
departing from the spirit of the present disclosure.
[0209] (1) In the above-described embodiments, the battery
monitoring apparatus 50 may be powered by both a first electric
power supply and a plurality of second electric power supplies. The
first electric power supply is configured with a plurality of the
battery cells 42 connected in series with each other. Moreover, the
first electric power supply has a positive-electrode-side electric
power supply terminal connected with that one of the positive
electrodes of the plurality of battery cells 42 which has a highest
electric potential and a negative-electrode-side electric power
supply terminal connected with that one of the negative electrodes
of the plurality of battery cells 42 which has a lowest electric
potential. In contrast, each of the second electric power supplies
is configured with a corresponding one of the battery cells 42.
Moreover, each of the second electric power supplies has a pair of
positive-electrode-side and negative-electrode-side electric power
supply terminals connected respectively with the positive and
negative electrodes of the corresponding battery cell 42.
[0210] For example, in a modification shown in FIG. 15, the
communication unit 54, the AD converters 154 and 163, the signal
processing unit 155 or 201, the oscillating circuit 158, the
phase-shift circuit 160 and the DA converter 162 are shared by all
the battery cells 42. In addition, though the first multiplier 156,
the second multiplier 157 and the low-pass filters 159 and 161 are
not shown in FIG. 15, they may also be shared by all the battery
cells 42 in the case of the signal processing unit 155 being
employed to perform the two-phase lock-in detection.
[0211] Moreover, in the modification shown in FIG. 15, those
components of the battery monitoring apparatus 50 which are shared
by all the battery cells 42 are powered by a first electric power
supply 401 that are configured with a plurality of battery cells 42
connected in series with each other. In contrast, each component
set corresponding to only one of the battery cells 42 is powered by
a second electric power supply 402 that is configured with the
corresponding battery cell 42. In addition, the output voltage of
the first electric power supply 401 is higher than the output
voltage of each of the second electric power supplies 402.
[0212] Furthermore, in the modification shown in FIG. 15,
multiplexers 302-304 are employed to perform switching of various
signals, such as the DC voltage, the response signal and the
command signal, between the battery cells 42.
[0213] (2) In the above-described embodiments, the battery
monitoring apparatus 50 may be modified to further perform an
equalization process for equalizing the states of charge and/or
voltages of the battery cells 42. Specifically, the equalization
process is a process for causing the battery cell(s) 42 having a
higher SOC (i.e., state of charge) than the other battery cell(s)
42 to discharge and thereby equalizing the states of charge of all
the battery cells 42. Consequently, it is possible to prevent the
occurrence of a phenomenon where some of the battery cells 42
become overcharged.
[0214] Moreover, in the case of the battery monitoring apparatus 50
being modified to further perform the equalization process, each of
the battery cells 42 may be caused by the corresponding current
modulation circuit 56 to discharge. In this case, the battery
monitoring apparatus 50 also functions as a discharge control
unit.
[0215] For example, in the first embodiment, the equalization
process may be performed by the microcomputer 53 as follows. Upon
receipt of a discharge command that is issued by the ECU 60 based
on the SOC of the battery cell 42 or upon the SOC or voltage of the
battery cell 42 exceeding a predetermine threshold, the
microcomputer 53 sends the command signal to the current modulation
circuit 56. Then, upon receipt of the command signal, the current
modulation circuit 56 causes a periodic-function signal (e.g., a
sine-wave or rectangular-wave signal) or a DC signal to be
outputted from the battery cell 42. Moreover, the microcomputer 53
continues sending the command signal to the current modulation
circuit 56 until the discharge command has been terminated or the
SOC or voltage of the battery cell 42 has been lowered below the
predetermined threshold.
[0216] In addition, in the second to the sixth embodiments, the
equalization process may be similarly performed by the
microcomputer 53 or by the signal processing unit 155 or 201.
[0217] Furthermore, the complex impedance of the battery cell 42
may be calculated based on the response signal of the battery cell
42 to the sine-wave signal that is outputted for performing the
equalization process. In this case, it is possible to suppress the
consumption of electric power of the battery cell 42.
[0218] In addition, the strength of the sine-wave signal outputted
for performing the equalization process is generally set to be low
(or weak) for suppressing the electric power consumption and
minimizing the size of the apparatus. Therefore, the battery
monitoring apparatuses 50 according to the second and fifth
embodiments, which are configured to perform the two-phase lock-in
detection, are particularly suitable for performing the
equalization process.
[0219] (3) In the above-described embodiments, the filter unit 55
is implemented by the semiconductor elements. Alternatively, the
filter unit 55 may be implemented by, instead of or in combination
with the semiconductor elements, wirings, connector contacts, and
pattern wirings and/or solid patterns formed on a printed
board.
[0220] (4) In the above-described embodiments, a filter circuit may
be provided between the current modulation circuit 56 and the
input/output unit 52 (or the DA converter 162). In this case, it is
possible to suppress, with the filter circuit, occurrence of an
error in the waveform of the command signal during the
digital-to-analog conversion of the command signal.
[0221] (5) In the above-described embodiments, some or all of the
differential amplifier 151, the preamplifier 152, the signal switch
153, the AD converters 154 and 163, the signal processing unit 155,
the first multiplier 156, the second multiplier 157, the low-pass
filters 159 and 161, the oscillating circuit 158, the phase-shift
circuit 160, the DA converter 162, the feedback circuit 56d and the
current detection amplifier 56c may be realized by software.
[0222] (6) In the above-described second and third embodiments, the
capacitor C1 may be omitted from the battery monitoring apparatus
50.
[0223] (7) In the above-described embodiments, the feedback circuit
56d may be omitted from the battery monitoring apparatus 50.
Moreover, the current single flowing through the resistor 56b may
not be detected by the current detection amplifier 56c.
Furthermore, the microcomputer 53 and the signal processing unit
155 or 201 may have no feedback signal inputted thereinto.
[0224] (8) In the above-described embodiments, the DC voltage of
the battery cell 42 that is the monitoring target is detected by
the battery monitoring apparatus 50. However, the DC voltage of the
battery cell 42 may not be detected by the battery monitoring
apparatus 50.
[0225] (9) In the above-described second, third, fifth and sixth
embodiments, the signal switch 153 may be omitted from the battery
monitoring apparatus 50. In this case, the measured DC voltage may
be directly inputted the signal processing unit 155 or 201.
[0226] (10) In the above-described second, third, fifth and sixth
embodiments, the feedback signal may also be selected by the signal
switch 153. In other words, the signal switch 153 may alternatively
be configured to select between the DC voltage, the response signal
and the feedback signal. In this case, it is possible to omit the
AD converter 163 and perform all the analog-to-digital conversions
of the DC voltage, the response signal and the feedback signal
using the single AD converter 154.
[0227] (11) The battery monitoring apparatuses 50 according to the
above-described embodiments may be applied to a HEV (Hybrid
Electric Vehicle), an EV (Electric Vehicle), a PHV (Plug-in Hybrid
Vehicle), an automotive accessory battery, an electric aircraft, an
electric motorcycle and an electric ship.
[0228] (12) In the above-described embodiments, the battery cells
42 are connected in series with each other. Alternatively, the
battery cells 42 may be connected in parallel with each other.
[0229] (13) In the above-described second, third, fifth and sixth
embodiments, to prevent occurrence of aliasing during the
analog-to-digital conversion by the AD converter 154, a filter
circuit may be provided immediately before or after the
preamplifier 152, or immediately before the AD converter 154.
[0230] (14) In the above-described embodiments, each battery
monitoring apparatus 50 may be configured to monitor a state of one
battery module 41. In this case, the communications from the
communication units 54 of the battery monitoring apparatuses 50,
which respectively monitor the battery modules 41, to the ECU 60
may be isolated-communications having different electric potential
references. The isolated-communications may be realized using, for
example, an isolation transformer or capacitor.
[0231] (15) In the above-described second and fifth embodiments,
the feedback signal may also be lock-in-detected.
[0232] For example, FIG. 16 illustrates a complex impedance
calculating process in which two-phase lock-in detection is
performed on the feedback signal as well as on the response signal.
This process is repeatedly performed by the battery monitoring
apparatus 50 in a predetermined cycle.
[0233] In the complex impedance calculating process, first, in step
S401, the oscillating circuit 158 sets a measurement frequency of
the complex impedance within a predetermined frequency range. In
addition, the measurement frequency is determined by, for example,
the signal processing unit 155.
[0234] In step S402, the oscillating circuit 158 sets the frequency
of the sine-wave signal (or predetermined AC signal) based on the
measurement frequency set in step S401. Then, the oscillating
circuit 158 outputs the command signal, through the
digital-to-analog conversion by the DA converter 162, to the
current modulation circuit 56 via the command signal output
terminal 59a. As described previously, the command signal is
indicative of a command commanding the current modulation circuit
56 to cause the sine-wave signal to be outputted from the battery
cell 42. Upon receipt of the command signal, the current modulation
circuit 56 causes the sine-wave signal to be outputted from the
battery cell 42 that is the monitoring target, with the battery
cell 42 itself being the electric power source for the output of
the sine-wave signal. Consequently, the sine-wave signal is
outputted from the battery cell 42.
[0235] In step S403, the signal processing unit 155 measures the
feedback signal by the two-phase lock-in detection. Specifically,
the signal processing unit 155 multiplies the sine-wave signal (or
reference signal) commanded by the oscillating circuit 158 and the
inputted feedback signal together. Moreover, the signal processing
unit 155 multiplies a signal, which is obtained by shifting the
phase of the sine-wave signal commanded by the oscillating circuit
158 by 90.degree., and the inputted feedback signal together. Then,
based on the multiplication results, the signal processing unit 155
calculates both the amplitude and the phase of the feedback
signal.
[0236] In step S404, the signal processing unit 155 determines
whether the deviation between the calculated amplitude of the
feedback signal and an amplitude correction value is within a given
amplitude-deviation range. Here, the amplitude correction value
denotes the amplitude of the sine-wave signal desired to be
outputted from the battery cell 42.
[0237] If the determination in step S404 results in a "NO" answer,
then the process proceeds to step S405. In contrast, if the
determination in step S404 results in a "YES" answer, then the
process proceeds to step S407.
[0238] In step S405, the signal processing unit 155 further
determines whether the number of times of measurement of the
feedback signal in step S403 has been increased to become not
smaller than (i.e., greater than or equal to) a given number.
[0239] If the determination in step S405 results in a "NO" answer,
then the signal processing unit 155 increases the number of times
of measurement of the feedback signal by one. Thereafter, the
process returns to step S403 to repeat step S403 and the subsequent
steps.
[0240] On the other hand, if the determination in step S405 results
in a "YES" answer, then the process proceeds to step S406.
[0241] In step S406, the signal processing unit 155 calculates an
average value of the measured amplitudes of the feedback signal and
rewrites the amplitude correction value to the average value. Then,
the signal processing unit 155 clears the number of times of
measurement. Thereafter, the process proceeds to step S407.
[0242] In step S407, the signal processing unit 155 determines
whether the deviation between the phase of the feedback signal
calculated in step S403 and a phase correction value is within a
given phase-deviation range. Here, the phase correction value
denotes the phase of the sine-wave signal desired to be outputted
from the battery cell 42.
[0243] If the determination in step S407 results in a "NO" answer,
then the process proceeds to step S408. In contrast, if the
determination in step S407 results in a "YES" answer, then the
process proceeds to step S410.
[0244] In step S408, the signal processing unit 155 further
determines whether the number of times of measurement of the
feedback signal in step S403 has been increased to become not
smaller than (i.e., greater than or equal to) the given number.
[0245] If the determination in step S408 results in a "NO" answer,
then the signal processing unit 155 increases the number of times
of measurement of the feedback signal by one. Thereafter, the
process returns to step S403 to repeat step S403 and the subsequent
steps.
[0246] On the other hand, if the determination in step S408 results
in a "YES" answer, then the process proceeds to step S409.
[0247] In step S409, the signal processing unit 155 calculates an
average value of the measured phases of the feedback signal and
rewrites the phase correction value to the average value. Then, the
signal processing unit 155 clears the number of times of
measurement. Thereafter, the process proceeds to step S410.
[0248] In step S410, the signal processing unit 155 measures the
response signal by the two-phase lock-in detection. For example,
the response signal may be measured by performing steps S202, S205
and S206 of the complex impedance calculating process according to
the second embodiment (see FIG. 7).
[0249] In step S411, the signal processing unit 155 calculates,
based on the feedback signal and the signals (or values
respectively proportional to the real and imaginary parts of the
response signal) from the low-pass filters 159 and 161, at least
one of the real part, the imaginary part, the absolute value and
the phase of the complex impedance of the battery cell 42. Here,
the feedback signal is represented by both the amplitude correction
value and the phase correction value. The feedback signal is used
to correct (or eliminate) any deviation in amplitude or phase
between the current signal actually outputted from the battery cell
42 and the sine-wave signal desired to be outputted from the
battery cell 42.
[0250] In step S412, the signal processing unit 155 outputs the
calculation results to the ECU 60 via the communication unit 54.
Then, the complex impedance calculating process terminates.
[0251] In the above-described complex impedance calculating
process, the feedback signal is also measured by the two-phase
lock-in detection. Therefore, with the above process, it is
possible to accurately measure the current signal actually
outputted from the battery cell 42 even in an environment where
noise is present. Accordingly, using the feedback signal measured
by the two-phase lock-in detection, it is possible to further
improve the accuracy of calculation of the complex impedance of the
battery cell 42.
[0252] (16) In the above-described embodiments, the current signal
caused to be outputted from the battery cell 42 is not limited to
the sine-wave signal. The current signal may alternatively be other
AC signals, such as a rectangular-wave signal or a triangular-wave
signal.
[0253] (17) In the above-described embodiments, the ECU 60 may be
constituted of a plurality of ECUs. Moreover, the ECUs may be
provided to respectively perform different functions or to
respectively control different control targets. For example, the
ECUs may include a battery ECU and an inverter ECU.
[0254] (18) In the above-described embodiments, in the case of
performing the lock-in detection, the sine-wave signal commanded by
the oscillating circuit 158 is used as the first reference signal.
Alternatively, the detected signal (i.e., the feedback signal) may
be used as the first reference signal. Moreover, in the case of
performing the two-phase lock-in detection, a signal, which is
obtained by shifting the phase of the detected signal (i.e., the
feedback signal), may be used as the second reference signal.
[0255] (19) In the above-described embodiments, the battery cells
42 (or the battery modules 41 or the battery pack 40) may be
configured to be used as an electric power source for peripheral
circuits during the output of the sine-wave signal (or the output
of the response signal) therefrom according to the command signal.
In contrast, the battery cells 42 (or the battery modules 41 or the
battery pack 40) may also be configured to be not used as an
electric power source for peripheral circuits during the output of
the sine-wave signal (or the output of the response signal)
therefrom according to the command signal.
[0256] (20) In the above-described embodiments, as shown in FIG.
17, the second electrical paths 82 may be respectively merged with
the fourth electrical paths 84 into sixth electrical paths 86
(i.e., 86a and 86b); and the sixth electrical paths 86 may be
respectively joined to the electric power supply terminals 71
(i.e., 71a and 71b) of the battery cell 42. In this case, it is
possible to further reduce the number of the electrical paths of
the battery monitoring apparatus 50 joined to the electric power
supply terminals 71 of the battery cell 42.
[0257] In addition, the response signal and the DC voltage of the
battery cell 42 are inputted to the battery monitoring apparatus 50
at different times. Therefore, the response signal and the DC
voltage will not affect each other even if the second electrical
paths 82 are respectively merged with the fourth electrical paths
84.
[0258] (21) In the above-described embodiments, as shown in FIG.
18, the circuit board 72 may be configured to have protruding parts
72a each of which protrudes to a corresponding one of the electric
power supply terminals 71 (i.e., 71a and 71b) of the battery cells
42 in the longitudinal direction of the battery cells 42. Moreover,
the battery-cell-side end portions of the electrical paths may be
provided respectively on the protruding parts 72a of the circuit
board 72.
[0259] In addition, in the case of providing a plurality of circuit
boards 72 respectively for the battery cells 42, it is desirable to
configure all the circuit boards 72 to have the same shape and
size. In this case, it is possible to reduce the time and cost for
manufacturing the battery monitoring apparatuses 50.
[0260] The control units and control methods described in the
present disclosure may be realized by a dedicated computer which
includes a processor and a memory to perform one or more functions
through execution of a computer program. As an alternative, the
control units and control methods described in the present
disclosure may be realized by a dedicated computer which includes
one or more hardware logic circuits to perform one or more
functions. As another alternative, the control units and control
methods described in the present disclosure may be realized by a
dedicated computer which includes a processor and a memory to
perform one or more functions through execution of a computer
program as well as one or more hardware logic circuits to perform
one or more functions. In addition, the computer program may be
stored, as instructions executed by the computer, in a
computer-readable, non-transitory and tangible recording
medium.
* * * * *